Performance Tiles have their own datasource in order to view performance metrics for your teams.
Click “new report” and then select the Performance Management Datasource. You’ll need to define the date range that matches your Performance Tiles (e.g. 7 or 30 days), and select your specific User Group.
Your report will display all performance tile metrics (not just those that you selected for agents). To view a stack rank of agents by a specific metric, click the sort arrows in the appropriate column header.
Note that these metrics are generally already averages. As such there are no summary functions present.