[just another ref]

Originally Posted by jdw3018

I'm still trying to figure out how the defender could be contacted in the torso if he didn't get there first? Is there a rule against leaning backwards? Is that when an offensive player puts his leg between a defensive players legs (hence, causing the defensive player to "straddle" the offensive player) that it constituted illegal activity on the defender's part?

He got there first. The problem was that he wasn't there when A1 went airborne.

4-45-6: A defender may not "belly up" or use the lower part of the body or arms to cause contact outside his/her vertical plane which is a foul.

Sounds a lot like a description of this play to me.