I have used both the K-7 and K-5, with all of the DA* lenses, extensively in rain, sleet and snow. Never had a problem. It's been posted before, but here's a video I made after getting knocked over by an ocean wave, while shooting with a K-7 and DA* 300mm.
I've also had a camera on the outside of a vehicle, while driving through a rain storm, shooting a timelapse. Still need to put that together one of these days...
I have a friend who shot for 9 hours in a driving rain storm in Patagonian Andes in southern Chile with a K-7 and DA* 16-50mm.
They can take a lot, it's quite remarkable. I'm always wondering when that day will come when I finally push it to far. But it hasn't happened yet. I think watching a game in the rain should be fine. Just for back up, bring a waterproof camera case, or a regular case and a small trash bag. If it gets too heavy for you liking, just stash it for the rest of the game.