It sounds like Quentin is holding grudges on a TLR-like level: "Myself and Greinke have a history. It dates back a few years. You guys can look it up. It's documented. It could have been avoided. You can ask Zack about that. For me, I've been hit by many pitches in my career. I think you guys know that. I can tell you I've never responded in that fashion, so you guys can do your homework on that. For me, the situation is done. That's it." (from http://mlb.mlb.com/news/article.jsp?ymd=20130412&content_id=44551080&vkey=news_mlb&c_id=mlb) That said, Greinke threw down his glove, lowered his shoulder, and went at Quentin, too. What happened is just basic physics, he's going to take the majority of the impact considering he was barely moving and Quentin had a head start.