Picture this: Someone joins your league, doesn't like it, gives you a horrible rating, and leaves. 2 years later, that rating is still there. The league has gone to a different host and almost everyone is different. It's basically a different league. But yet, that 1 star rating stays there. And your league will never recover, because they're stuck with it.
What I'm suggesting is that after x amount of time, the rating goes away, to prevent outdated ratings, like the example I provided. It can be several months, a year, really anything. This would also prevent trolls that go from league to league, giving bad ratings.
I also think that stars should round, so that 4.8 is 5, not 4.5. But that's for another thread.
Thoughts?