There is currently a press photo of Keanu from the 1990 MTV Rock ‘n Jock event on ebay. Click on the photo to zoom in. It further enlarges nicely.
Complex has a post on the oral history of the event. The post includes the following Keanu mentions:
Kevin Seal: All I remember about the first game is looking across the outfield and Keanu Reeves is standing there perfectly still just like a plant, just perfectly still. I thought it was some kind of meditative practice. He seemed to be perfectly present in the sun. All that existed for him was that moment.
Byrnes: Keanu didn’t know the rules. He yelled, “I’m a Canadian,” after getting tagged out.
wyldstallyns4ever posted a 1:30 min clip from the event on youtube back in July 2008 for anyone interested in revisiting it.