Purdy - although there's contact, it still looks like he could have stayed on his feet to me. Felt the contact, leaned forward and went down.
He was tripped, it was a penalty. Players don't have to do everything they can to stay on their feet, in fact I believe that if you're tripped then you have every right to go to ground because time and time again officials won't award fouls when a player stays on his feet.