There are now two pages: Offense/Defense comps.
Navigation at the bottom
If you are on a mobile device you should click through to load the report here. The report seems to be heavy for Wix/Google's servers to handle on mobile embedded.
Select the year, then unselect all the schools, then select two schools.
You do have to click the button to unselect all the schools twice times for reasons known only to Data Studio.
You can select schools from different years by using the "School | Year" button, unselect all and then search schools.