Ok, we need to break down the entire play starting from the time Crabtree catches the ball.
The fact that his knee is down in the endzone at the start (this being the key word) of the catch is irrevelant. For a catch to be complete when it involves the player going to the ground, he has to maintain possession from the start of the catch to the point when his momentum is stopped (that's what the process of the catch is). Forward progress doesn't apply in this situation because of the fact that Crabtree is going to the ground, which means forward progress gets negated by the process of the catch rule. Forward progress would apply if Crabtree had jumped to catch the ball in the endzone and the defender pushed him across the goalline and Crabtree would have came down in the endzone without the push.
With that stated, for the catch to count, Crabtree needs to maintain control of the ball to the point where his body stops moving and the play is over. As he's rolling over, the nose of the ball touches the ground. The ball can touch the ground if the player maintains control of it, if it's moving it's an incomplete pass.
Lastly, since Crabtree wasn't touched by a defender when he was on the ground and went out of bounds on his own, the ball gets spotted where he went out of bounds.
If Crabtree runs that route one to two yards deeper, we're not even having this discussion.
[ Edited by linkboy on Nov 3, 2014 at 10:12 AM ]