Keri linked to this on Grantland:
I think this is an excellent analysis of the situation and that the comments are pretty intelligent.
If i'm Quentin, and with the history of getting hit three times by this guy and watching several of my teammates get hit as well, my initial conclusion is going to be that Grienke threw at me intentionally. I'm sure he wasn't thinking about game situation or anything like that.
He obviously shouldn't have charged the mound and he's obviously in the wrong, but again--Grienke could have avoided the whole situation if he had wanted to.