I also believe that Marshall intimidated the front line of St Johns a bit with he and Okafor in at the same time. Their height altered shots and they were able to get rebounds, get it to the guards, and settle into a lead which made St johns try and rush it even more.
I have to tell you I was at the Miami game as the team came out. I was standing down at the aisle where the team exits and runs into Cameron. I'm 6'4" and Quinn Cook is as big as me. John Scheyer has to be about 6'7".