This is the best idea I've seen amid what basically amounts to 13 pages of repetition.
Completely random isn't the answer, neither should it be completely based on ratings. Some combination of those factors, ratings and random chance would be the best plan.
Now, to post briefly about what seems to be the main point in this thread. Personally I'm not against button mashing per se, but the points made about it being exploited are pretty valid too. I must say I actually like how 2k did the tackle breaking thing, it wasn't intrusive, and it worked.
Can Ian or someone else say whether it is possible during online games to work out if someone is using a turbo controller (maybe by checking for unrealistically short gaps between button presses?)?
If that is possible, it gives a very easy answer to the cheese, if not, then I'm still not against button mashing solely for that reason. As was said in an earlier post, turbo controllers are hardly ten-a-penny these days, so it isn't a huge problem.
I also think there should be as many pile up animations (and possible outcomes) as possible.