diff --git a/src/legacy/core_plugins/vis_type_timeseries/public/components/aggs/agg_row.js b/src/legacy/core_plugins/vis_type_timeseries/public/components/aggs/agg_row.js
index b07e1cef4fc8..a2f1640904dd 100644
--- a/src/legacy/core_plugins/vis_type_timeseries/public/components/aggs/agg_row.js
+++ b/src/legacy/core_plugins/vis_type_timeseries/public/components/aggs/agg_row.js
@@ -22,14 +22,13 @@ import React from 'react';
 import { last } from 'lodash';
 import { AddDeleteButtons } from '../add_delete_buttons';
 import { EuiIcon, EuiFlexGroup, EuiFlexItem } from '@elastic/eui';
-import { injectI18n } from '@kbn/i18n/react';
 import { SeriesDragHandler } from '../series_drag_handler';
+import { i18n } from '@kbn/i18n';
 
-function AggRowUi(props) {
+export function AggRow(props) {
   let iconType = 'eyeClosed';
   let iconColor = 'subdued';
   const lastSibling = last(props.siblings);
-  const { intl } = props;
 
   if (lastSibling.id === props.model.id) {
     iconType = 'eye';
@@ -57,12 +56,10 @@ function AggRowUi(props) {
         <EuiFlexItem grow={false}>
           <AddDeleteButtons
             testSubj="addMetric"
-            addTooltip={intl.formatMessage({
-              id: 'visTypeTimeseries.aggRow.addMetricButtonTooltip',
+            addTooltip={i18n.translate('visTypeTimeseries.aggRow.addMetricButtonTooltip', {
               defaultMessage: 'Add Metric',
             })}
-            deleteTooltip={intl.formatMessage({
-              id: 'visTypeTimeseries.aggRow.deleteMetricButtonTooltip',
+            deleteTooltip={i18n.translate('visTypeTimeseries.aggRow.deleteMetricButtonTooltip', {
               defaultMessage: 'Delete Metric',
             })}
             onAdd={props.onAdd}
@@ -75,7 +72,7 @@ function AggRowUi(props) {
   );
 }
 
-AggRowUi.propTypes = {
+AggRow.propTypes = {
   disableDelete: PropTypes.bool,
   model: PropTypes.object,
   onAdd: PropTypes.func,
@@ -83,5 +80,3 @@ AggRowUi.propTypes = {
   siblings: PropTypes.array,
   dragHandleProps: PropTypes.object,
 };
-
-export const AggRow = injectI18n(AggRowUi);
diff --git a/src/legacy/core_plugins/vis_type_timeseries/public/components/aggs/agg_select.js b/src/legacy/core_plugins/vis_type_timeseries/public/components/aggs/agg_select.js
index a6180e83fd39..f93dee14d0ee 100644
--- a/src/legacy/core_plugins/vis_type_timeseries/public/components/aggs/agg_select.js
+++ b/src/legacy/core_plugins/vis_type_timeseries/public/components/aggs/agg_select.js
@@ -226,7 +226,7 @@ function filterByPanelType(panelType) {
 }
 
 function AggSelectUi(props) {
-  const { siblings, panelType, value, onChange, intl, uiRestrictions, ...rest } = props;
+  const { siblings, panelType, value, onChange, uiRestrictions, ...rest } = props;
 
   const selectedOptions = allAggOptions.filter(option => {
     return value === option.value && isMetricEnabled(option.value, uiRestrictions);
@@ -247,8 +247,7 @@ function AggSelectUi(props) {
 
     options = [
       {
-        label: intl.formatMessage({
-          id: 'visTypeTimeseries.aggSelect.aggGroups.metricAggLabel',
+        label: i18n.translate('visTypeTimeseries.aggSelect.aggGroups.metricAggLabel', {
           defaultMessage: 'Metric Aggregations',
         }),
         options: metricAggs.map(agg => ({
@@ -257,22 +256,19 @@ function AggSelectUi(props) {
         })),
       },
       {
-        label: intl.formatMessage({
-          id: 'visTypeTimeseries.aggSelect.aggGroups.parentPipelineAggLabel',
+        label: i18n.translate('visTypeTimeseries.aggSelect.aggGroups.parentPipelineAggLabel', {
           defaultMessage: 'Parent Pipeline Aggregations',
         }),
         options: pipelineAggs.filter(filterByPanelType(panelType)).map(disableSiblingAggs),
       },
       {
-        label: intl.formatMessage({
-          id: 'visTypeTimeseries.aggSelect.aggGroups.siblingPipelineAggLabel',
+        label: i18n.translate('visTypeTimeseries.aggSelect.aggGroups.siblingPipelineAggLabel', {
           defaultMessage: 'Sibling Pipeline Aggregations',
         }),
         options: siblingAggs.map(disableSiblingAggs),
       },
       {
-        label: intl.formatMessage({
-          id: 'visTypeTimeseries.aggSelect.aggGroups.specialAggLabel',
+        label: i18n.translate('visTypeTimeseries.aggSelect.aggGroups.specialAggLabel', {
           defaultMessage: 'Special Aggregations',
         }),
         options: specialAggs.map(disableSiblingAggs),
@@ -289,8 +285,7 @@ function AggSelectUi(props) {
     <div data-test-subj="aggSelector">
       <EuiComboBox
         isClearable={false}
-        placeholder={intl.formatMessage({
-          id: 'visTypeTimeseries.aggSelect.selectAggPlaceholder',
+        placeholder={i18n.translate('visTypeTimeseries.aggSelect.selectAggPlaceholder', {
           defaultMessage: 'Select aggregation',
         })}
         options={options}
diff --git a/src/legacy/core_plugins/vis_type_timeseries/public/components/aggs/calculation.js b/src/legacy/core_plugins/vis_type_timeseries/public/components/aggs/calculation.js
index 76306ecf2899..297530f8965e 100644
--- a/src/legacy/core_plugins/vis_type_timeseries/public/components/aggs/calculation.js
+++ b/src/legacy/core_plugins/vis_type_timeseries/public/components/aggs/calculation.js
@@ -18,16 +18,14 @@
  */
 
 import PropTypes from 'prop-types';
-import React, { Component } from 'react';
-import _ from 'lodash';
-import uuid from 'uuid';
+import React, { useEffect } from 'react';
 import { AggRow } from './agg_row';
 import { AggSelect } from './agg_select';
 
 import { createChangeHandler } from '../lib/create_change_handler';
 import { createSelectHandler } from '../lib/create_select_handler';
 import { createTextHandler } from '../lib/create_text_handler';
-import { CalculationVars } from './vars';
+import { CalculationVars, newVariable } from './vars';
 import { FormattedMessage } from '@kbn/i18n/react';
 
 import {
@@ -41,105 +39,100 @@ import {
   EuiSpacer,
 } from '@elastic/eui';
 
-export class CalculationAgg extends Component {
-  UNSAFE_componentWillMount() {
-    if (!this.props.model.variables) {
-      this.props.onChange(
-        _.assign({}, this.props.model, {
-          variables: [{ id: uuid.v1() }],
-        })
-      );
+const checkModel = model => Array.isArray(model.variables) && model.script !== undefined;
+
+export function CalculationAgg(props) {
+  const htmlId = htmlIdGenerator();
+  const { siblings, model } = props;
+
+  const handleChange = createChangeHandler(props.onChange, model);
+  const handleSelectChange = createSelectHandler(handleChange);
+  const handleTextChange = createTextHandler(handleChange);
+
+  useEffect(() => {
+    if (!checkModel(model)) {
+      handleChange({
+        variables: [newVariable()],
+        script: '',
+      });
     }
-  }
+  }, [handleChange, model]);
 
-  render() {
-    const { siblings } = this.props;
-
-    const defaults = { script: '' };
-    const model = { ...defaults, ...this.props.model };
-
-    const handleChange = createChangeHandler(this.props.onChange, model);
-    const handleSelectChange = createSelectHandler(handleChange);
-    const handleTextChange = createTextHandler(handleChange);
-
-    const htmlId = htmlIdGenerator();
-
-    return (
-      <AggRow
-        disableDelete={this.props.disableDelete}
-        model={this.props.model}
-        onAdd={this.props.onAdd}
-        onDelete={this.props.onDelete}
-        siblings={this.props.siblings}
-        dragHandleProps={this.props.dragHandleProps}
-      >
-        <EuiFlexGroup direction="column" gutterSize="l">
-          <EuiFlexItem>
-            <EuiFormLabel htmlFor={htmlId('aggregation')}>
-              <FormattedMessage
-                id="visTypeTimeseries.calculation.aggregationLabel"
-                defaultMessage="Aggregation"
-              />
-            </EuiFormLabel>
-            <EuiSpacer size="xs" />
-            <AggSelect
-              id={htmlId('aggregation')}
-              panelType={this.props.panel.type}
-              siblings={this.props.siblings}
-              value={model.type}
-              onChange={handleSelectChange('type')}
+  return (
+    <AggRow
+      disableDelete={props.disableDelete}
+      model={props.model}
+      onAdd={props.onAdd}
+      onDelete={props.onDelete}
+      siblings={props.siblings}
+      dragHandleProps={props.dragHandleProps}
+    >
+      <EuiFlexGroup direction="column" gutterSize="l">
+        <EuiFlexItem>
+          <EuiFormLabel htmlFor={htmlId('aggregation')}>
+            <FormattedMessage
+              id="visTypeTimeseries.calculation.aggregationLabel"
+              defaultMessage="Aggregation"
             />
-          </EuiFlexItem>
+          </EuiFormLabel>
+          <EuiSpacer size="xs" />
+          <AggSelect
+            id={htmlId('aggregation')}
+            panelType={props.panel.type}
+            siblings={props.siblings}
+            value={model.type}
+            onChange={handleSelectChange('type')}
+          />
+        </EuiFlexItem>
 
-          <EuiFlexItem>
-            <EuiFormLabel htmlFor={htmlId('variables')}>
-              <FormattedMessage
-                id="visTypeTimeseries.calculation.variablesLabel"
-                defaultMessage="Variables"
-              />
-            </EuiFormLabel>
-            <EuiSpacer size="xs" />
-            <CalculationVars
-              id={htmlId('variables')}
-              metrics={siblings}
-              onChange={handleChange}
-              name="variables"
-              model={model}
+        <EuiFlexItem>
+          <EuiFormLabel htmlFor={htmlId('variables')}>
+            <FormattedMessage
+              id="visTypeTimeseries.calculation.variablesLabel"
+              defaultMessage="Variables"
             />
-          </EuiFlexItem>
+          </EuiFormLabel>
+          <EuiSpacer size="xs" />
+          <CalculationVars
+            id={htmlId('variables')}
+            metrics={siblings}
+            onChange={handleChange}
+            name="variables"
+            model={model}
+          />
+        </EuiFlexItem>
 
-          <EuiFlexItem>
-            <EuiFormRow
-              id={htmlId('painless')}
-              label={
+        <EuiFlexItem>
+          <EuiFormRow
+            id={htmlId('painless')}
+            label={
+              <FormattedMessage
+                id="visTypeTimeseries.calculation.painlessScriptLabel"
+                defaultMessage="Painless Script"
+              />
+            }
+            fullWidth
+            helpText={
+              <div>
                 <FormattedMessage
-                  id="visTypeTimeseries.calculation.painlessScriptLabel"
-                  defaultMessage="Painless Script"
-                />
-              }
-              fullWidth
-              helpText={
-                <div>
-                  <FormattedMessage
-                    id="visTypeTimeseries.calculation.painlessScriptDescription"
-                    defaultMessage="Variables are keys on the {params} object, i.e. {paramsName}. To access the bucket
+                  id="visTypeTimeseries.calculation.painlessScriptDescription"
+                  defaultMessage="Variables are keys on the {params} object, i.e. {paramsName}. To access the bucket
                     interval (in milliseconds) use {paramsInterval}."
-                    values={{
-                      params: <EuiCode>params</EuiCode>,
-                      paramsName: <EuiCode>params.&lt;name&gt;</EuiCode>,
-                      paramsInterval: <EuiCode>params._interval</EuiCode>,
-                    }}
-                  />
-                </div>
-              }
-            >
-              <EuiTextArea onChange={handleTextChange('script')} value={model.script} fullWidth />
-            </EuiFormRow>
-          </EuiFlexItem>
-        </EuiFlexGroup>
-      </AggRow>
-    );
-  }
+                  values={{
+                    params: <EuiCode>params</EuiCode>,
+                    paramsName: <EuiCode>params.&lt;name&gt;</EuiCode>,
+                    paramsInterval: <EuiCode>params._interval</EuiCode>,
+                  }}
+                />
+              </div>
+            }
+          >
+            <EuiTextArea onChange={handleTextChange('script')} value={model.script} fullWidth />
+          </EuiFormRow>
+        </EuiFlexItem>
+      </EuiFlexGroup>
+    </AggRow>
+  );
 }
 
 CalculationAgg.propTypes = {
diff --git a/src/legacy/core_plugins/vis_type_timeseries/public/components/aggs/math.js b/src/legacy/core_plugins/vis_type_timeseries/public/components/aggs/math.js
index c62012927f95..5ffcef12c3fc 100644
--- a/src/legacy/core_plugins/vis_type_timeseries/public/components/aggs/math.js
+++ b/src/legacy/core_plugins/vis_type_timeseries/public/components/aggs/math.js
@@ -17,17 +17,15 @@
  * under the License.
  */
 
-import React, { Component } from 'react';
+import React, { useEffect } from 'react';
 import PropTypes from 'prop-types';
-import _ from 'lodash';
-import uuid from 'uuid';
 import { AggRow } from './agg_row';
 import { AggSelect } from './agg_select';
 
 import { createChangeHandler } from '../lib/create_change_handler';
 import { createSelectHandler } from '../lib/create_select_handler';
 import { createTextHandler } from '../lib/create_text_handler';
-import { CalculationVars } from './vars';
+import { CalculationVars, newVariable } from './vars';
 import {
   htmlIdGenerator,
   EuiFlexGroup,
@@ -41,125 +39,121 @@ import {
 } from '@elastic/eui';
 import { FormattedMessage } from '@kbn/i18n/react';
 
-export class MathAgg extends Component {
-  UNSAFE_componentWillMount() {
-    if (!this.props.model.variables) {
-      this.props.onChange(
-        _.assign({}, this.props.model, {
-          variables: [{ id: uuid.v1() }],
-        })
-      );
+const checkModel = model => Array.isArray(model.variables) && model.script !== undefined;
+
+export function MathAgg(props) {
+  const { siblings, model } = props;
+  const htmlId = htmlIdGenerator();
+
+  const handleChange = createChangeHandler(props.onChange, model);
+  const handleSelectChange = createSelectHandler(handleChange);
+  const handleTextChange = createTextHandler(handleChange);
+
+  useEffect(() => {
+    if (!checkModel(model)) {
+      handleChange({
+        variables: [newVariable()],
+        script: '',
+      });
     }
-  }
+  }, [handleChange, model]);
 
-  render() {
-    const { siblings } = this.props;
-    const htmlId = htmlIdGenerator();
-
-    const defaults = { script: '' };
-    const model = { ...defaults, ...this.props.model };
-
-    const handleChange = createChangeHandler(this.props.onChange, model);
-    const handleSelectChange = createSelectHandler(handleChange);
-    const handleTextChange = createTextHandler(handleChange);
-
-    return (
-      <AggRow
-        disableDelete={this.props.disableDelete}
-        model={this.props.model}
-        onAdd={this.props.onAdd}
-        onDelete={this.props.onDelete}
-        siblings={this.props.siblings}
-        dragHandleProps={this.props.dragHandleProps}
-      >
-        <EuiFlexGroup direction="column" gutterSize="l">
-          <EuiFlexItem>
-            <EuiFormLabel htmlFor={htmlId('aggregation')}>
-              <FormattedMessage
-                id="visTypeTimeseries.math.aggregationLabel"
-                defaultMessage="Aggregation"
-              />
-            </EuiFormLabel>
-            <EuiSpacer size="xs" />
-            <AggSelect
-              id={htmlId('aggregation')}
-              siblings={this.props.siblings}
-              value={model.type}
-              onChange={handleSelectChange('type')}
+  return (
+    <AggRow
+      disableDelete={props.disableDelete}
+      model={props.model}
+      onAdd={props.onAdd}
+      onDelete={props.onDelete}
+      siblings={props.siblings}
+      dragHandleProps={props.dragHandleProps}
+    >
+      <EuiFlexGroup direction="column" gutterSize="l">
+        <EuiFlexItem>
+          <EuiFormLabel htmlFor={htmlId('aggregation')}>
+            <FormattedMessage
+              id="visTypeTimeseries.math.aggregationLabel"
+              defaultMessage="Aggregation"
             />
-          </EuiFlexItem>
+          </EuiFormLabel>
+          <EuiSpacer size="xs" />
+          <AggSelect
+            id={htmlId('aggregation')}
+            siblings={props.siblings}
+            value={model.type}
+            onChange={handleSelectChange('type')}
+          />
+        </EuiFlexItem>
 
-          <EuiFlexItem>
-            <EuiFormLabel htmlFor={htmlId('variables')}>
-              <FormattedMessage
-                id="visTypeTimeseries.math.variablesLabel"
-                defaultMessage="Variables"
-              />
-            </EuiFormLabel>
-            <EuiSpacer size="xs" />
-            <CalculationVars
-              id={htmlId('variables')}
-              metrics={siblings}
-              onChange={handleChange}
-              name="variables"
-              model={model}
-              includeSiblings={true}
+        <EuiFlexItem>
+          <EuiFormLabel htmlFor={htmlId('variables')}>
+            <FormattedMessage
+              id="visTypeTimeseries.math.variablesLabel"
+              defaultMessage="Variables"
             />
-          </EuiFlexItem>
+          </EuiFormLabel>
+          <EuiSpacer size="xs" />
+          <CalculationVars
+            id={htmlId('variables')}
+            metrics={siblings}
+            onChange={handleChange}
+            name="variables"
+            model={model}
+            includeSiblings={true}
+          />
+        </EuiFlexItem>
 
-          <EuiFlexItem>
-            <EuiFormRow
-              id="mathExpressionInput"
-              label={
-                <FormattedMessage
-                  id="visTypeTimeseries.math.expressionLabel"
-                  defaultMessage="Expression"
-                />
-              }
-              fullWidth
-              helpText={
-                <FormattedMessage
-                  id="visTypeTimeseries.math.expressionDescription"
-                  defaultMessage="This field uses basic math expressions (see {link}) - Variables are keys on the {params} object,
+        <EuiFlexItem>
+          <EuiFormRow
+            id="mathExpressionInput"
+            label={
+              <FormattedMessage
+                id="visTypeTimeseries.math.expressionLabel"
+                defaultMessage="Expression"
+              />
+            }
+            fullWidth
+            helpText={
+              <FormattedMessage
+                id="visTypeTimeseries.math.expressionDescription"
+                defaultMessage="This field uses basic math expressions (see {link}) - Variables are keys on the {params} object,
                 i.e. {paramsName} To access all the data use {paramsValues} for an array of the values and {paramsTimestamps} for
                 an array of the timestamps. {paramsTimestamp} is available for the current bucket's timestamp,
                 {paramsIndex} is available for the current bucket's index, and {paramsInterval}s available for
                 the interval in milliseconds."
-                  values={{
-                    link: (
-                      <EuiLink
-                        href="https://github.com/elastic/tinymath/blob/master/docs/functions.md"
-                        target="_blank"
-                      >
-                        <FormattedMessage
-                          id="visTypeTimeseries.math.expressionDescription.tinyMathLinkText"
-                          defaultMessage="TinyMath"
-                        />
-                      </EuiLink>
-                    ),
-                    params: <EuiCode>params</EuiCode>,
-                    paramsName: <EuiCode>params.&lt;name&gt;</EuiCode>,
-                    paramsValues: <EuiCode>params._all.&lt;name&gt;.values</EuiCode>,
-                    paramsTimestamps: <EuiCode>params._all.&lt;name&gt;.timestamps</EuiCode>,
-                    paramsTimestamp: <EuiCode>params._timestamp</EuiCode>,
-                    paramsIndex: <EuiCode>params._index</EuiCode>,
-                    paramsInterval: <EuiCode>params._interval</EuiCode>,
-                  }}
-                />
-              }
-            >
-              <EuiTextArea
-                data-test-subj="mathExpression"
-                onChange={handleTextChange('script')}
-                fullWidth
-                value={model.script}
+                values={{
+                  link: (
+                    <EuiLink
+                      href="https://github.com/elastic/tinymath/blob/master/docs/functions.md"
+                      target="_blank"
+                    >
+                      <FormattedMessage
+                        id="visTypeTimeseries.math.expressionDescription.tinyMathLinkText"
+                        defaultMessage="TinyMath"
+                      />
+                    </EuiLink>
+                  ),
+                  params: <EuiCode>params</EuiCode>,
+                  paramsName: <EuiCode>params.&lt;name&gt;</EuiCode>,
+                  paramsValues: <EuiCode>params._all.&lt;name&gt;.values</EuiCode>,
+                  paramsTimestamps: <EuiCode>params._all.&lt;name&gt;.timestamps</EuiCode>,
+                  paramsTimestamp: <EuiCode>params._timestamp</EuiCode>,
+                  paramsIndex: <EuiCode>params._index</EuiCode>,
+                  paramsInterval: <EuiCode>params._interval</EuiCode>,
+                }}
               />
-            </EuiFormRow>
-          </EuiFlexItem>
-        </EuiFlexGroup>
-      </AggRow>
-    );
-  }
+            }
+          >
+            <EuiTextArea
+              data-test-subj="mathExpression"
+              onChange={handleTextChange('script')}
+              fullWidth
+              value={model.script}
+            />
+          </EuiFormRow>
+        </EuiFlexItem>
+      </EuiFlexGroup>
+    </AggRow>
+  );
 }
 
 MathAgg.propTypes = {
diff --git a/src/legacy/core_plugins/vis_type_timeseries/public/components/aggs/percentile.js b/src/legacy/core_plugins/vis_type_timeseries/public/components/aggs/percentile.js
index 3ce5be5b6875..500bba14d66c 100644
--- a/src/legacy/core_plugins/vis_type_timeseries/public/components/aggs/percentile.js
+++ b/src/legacy/core_plugins/vis_type_timeseries/public/components/aggs/percentile.js
@@ -18,8 +18,7 @@
  */
 
 import PropTypes from 'prop-types';
-import React, { Component } from 'react';
-import _ from 'lodash';
+import React, { useEffect } from 'react';
 import { AggSelect } from './agg_select';
 import { FieldSelect } from './field_select';
 import { AggRow } from './agg_row';
@@ -39,82 +38,78 @@ import { Percentiles, newPercentile } from './percentile_ui';
 
 const RESTRICT_FIELDS = [KBN_FIELD_TYPES.NUMBER];
 
-export class PercentileAgg extends Component {
-  // eslint-disable-line react/no-multi-comp
+const checkModel = model => Array.isArray(model.percentiles);
 
-  UNSAFE_componentWillMount() {
-    if (!this.props.model.percentiles) {
-      this.props.onChange(
-        _.assign({}, this.props.model, {
-          percentiles: [newPercentile({ value: 50 })],
-        })
-      );
+export function PercentileAgg(props) {
+  const { series, model, panel, fields } = props;
+  const htmlId = htmlIdGenerator();
+
+  const handleChange = createChangeHandler(props.onChange, model);
+  const handleSelectChange = createSelectHandler(handleChange);
+  const indexPattern =
+    (series.override_index_pattern && series.series_index_pattern) || panel.index_pattern;
+
+  useEffect(() => {
+    if (!checkModel(model)) {
+      handleChange({
+        percentiles: [newPercentile({ value: 50 })],
+      });
     }
-  }
+  }, [handleChange, model]);
 
-  render() {
-    const { series, model, panel, fields } = this.props;
-
-    const handleChange = createChangeHandler(this.props.onChange, model);
-    const handleSelectChange = createSelectHandler(handleChange);
-    const indexPattern =
-      (series.override_index_pattern && series.series_index_pattern) || panel.index_pattern;
-    const htmlId = htmlIdGenerator();
-
-    return (
-      <AggRow
-        disableDelete={this.props.disableDelete}
-        model={this.props.model}
-        onAdd={this.props.onAdd}
-        onDelete={this.props.onDelete}
-        siblings={this.props.siblings}
-        dragHandleProps={this.props.dragHandleProps}
-      >
-        <EuiFlexGroup gutterSize="s">
-          <EuiFlexItem>
-            <EuiFormLabel htmlFor={htmlId('aggregation')}>
-              <FormattedMessage
-                id="visTypeTimeseries.percentile.aggregationLabel"
-                defaultMessage="Aggregation"
-              />
-            </EuiFormLabel>
-            <EuiSpacer size="xs" />
-            <AggSelect
-              id={htmlId('aggregation')}
-              panelType={this.props.panel.type}
-              siblings={this.props.siblings}
-              value={model.type}
-              onChange={handleSelectChange('type')}
+  return (
+    <AggRow
+      disableDelete={props.disableDelete}
+      model={props.model}
+      onAdd={props.onAdd}
+      onDelete={props.onDelete}
+      siblings={props.siblings}
+      dragHandleProps={props.dragHandleProps}
+    >
+      <EuiFlexGroup gutterSize="s">
+        <EuiFlexItem>
+          <EuiFormLabel htmlFor={htmlId('aggregation')}>
+            <FormattedMessage
+              id="visTypeTimeseries.percentile.aggregationLabel"
+              defaultMessage="Aggregation"
             />
-          </EuiFlexItem>
-          <EuiFlexItem>
-            <EuiFormRow
-              id={htmlId('field')}
-              label={
-                <FormattedMessage
-                  id="visTypeTimeseries.percentile.fieldLabel"
-                  defaultMessage="Field"
-                />
-              }
-            >
-              <FieldSelect
-                fields={fields}
-                type={model.type}
-                restrict={RESTRICT_FIELDS}
-                indexPattern={indexPattern}
-                value={model.field}
-                onChange={handleSelectChange('field')}
+          </EuiFormLabel>
+          <EuiSpacer size="xs" />
+          <AggSelect
+            id={htmlId('aggregation')}
+            panelType={props.panel.type}
+            siblings={props.siblings}
+            value={model.type}
+            onChange={handleSelectChange('type')}
+          />
+        </EuiFlexItem>
+        <EuiFlexItem>
+          <EuiFormRow
+            id={htmlId('field')}
+            label={
+              <FormattedMessage
+                id="visTypeTimeseries.percentile.fieldLabel"
+                defaultMessage="Field"
               />
-            </EuiFormRow>
-          </EuiFlexItem>
-        </EuiFlexGroup>
+            }
+          >
+            <FieldSelect
+              fields={fields}
+              type={model.type}
+              restrict={RESTRICT_FIELDS}
+              indexPattern={indexPattern}
+              value={model.field}
+              onChange={handleSelectChange('field')}
+            />
+          </EuiFormRow>
+        </EuiFlexItem>
+      </EuiFlexGroup>
 
-        <EuiSpacer size="m" />
+      <EuiSpacer size="m" />
 
-        <Percentiles onChange={handleChange} name="percentiles" model={model} panel={panel} />
-      </AggRow>
-    );
-  }
+      <Percentiles onChange={handleChange} name="percentiles" model={model} panel={panel} />
+    </AggRow>
+  );
 }
 
 PercentileAgg.propTypes = {
diff --git a/src/legacy/core_plugins/vis_type_timeseries/public/components/aggs/vars.js b/src/legacy/core_plugins/vis_type_timeseries/public/components/aggs/vars.js
index 8553f08af135..3d4ce601c724 100644
--- a/src/legacy/core_plugins/vis_type_timeseries/public/components/aggs/vars.js
+++ b/src/legacy/core_plugins/vis_type_timeseries/public/components/aggs/vars.js
@@ -19,14 +19,17 @@
 
 import PropTypes from 'prop-types';
 import React, { Component } from 'react';
+import uuid from 'uuid';
+import { i18n } from '@kbn/i18n';
 import _ from 'lodash';
 import { AddDeleteButtons } from '../add_delete_buttons';
 import { collectionActions } from '../lib/collection_actions';
 import { MetricSelect } from './metric_select';
 import { EuiFlexGroup, EuiFlexItem, EuiFieldText } from '@elastic/eui';
-import { injectI18n } from '@kbn/i18n/react';
 
-class CalculationVarsUi extends Component {
+export const newVariable = opts => ({ id: uuid.v1(), name: '', field: '', ...opts });
+
+export class CalculationVars extends Component {
   constructor(props) {
     super(props);
     this.renderRow = this.renderRow.bind(this);
@@ -42,21 +45,19 @@ class CalculationVarsUi extends Component {
   }
 
   renderRow(row, i, items) {
-    const handleAdd = collectionActions.handleAdd.bind(null, this.props);
+    const handleAdd = collectionActions.handleAdd.bind(null, this.props, newVariable);
     const handleDelete = collectionActions.handleDelete.bind(null, this.props, row);
-    const { intl } = this.props;
+
     return (
       <EuiFlexItem key={row.id} data-test-subj="varRow">
         <EuiFlexGroup alignItems="center" responsive={false} gutterSize="s">
           <EuiFlexItem>
             <EuiFieldText
               className="tvbAggs__varName"
-              aria-label={intl.formatMessage({
-                id: 'visTypeTimeseries.vars.variableNameAriaLabel',
+              aria-label={i18n.translate('visTypeTimeseries.vars.variableNameAriaLabel', {
                 defaultMessage: 'Variable name',
               })}
-              placeholder={intl.formatMessage({
-                id: 'visTypeTimeseries.vars.variableNamePlaceholder',
+              placeholder={i18n.translate('visTypeTimeseries.vars.variableNamePlaceholder', {
                 defaultMessage: 'Variable name',
               })}
               onChange={this.handleChange(row, 'name')}
@@ -97,17 +98,15 @@ class CalculationVarsUi extends Component {
   }
 }
 
-CalculationVarsUi.defaultProps = {
+CalculationVars.defaultProps = {
   name: 'variables',
   includeSiblings: false,
 };
 
-CalculationVarsUi.propTypes = {
+CalculationVars.propTypes = {
   metrics: PropTypes.array,
   model: PropTypes.object,
   name: PropTypes.string,
   onChange: PropTypes.func,
   includeSiblings: PropTypes.bool,
 };
-
-export const CalculationVars = injectI18n(CalculationVarsUi);