Also, looking at the clips I still don't think Gabbert intended to go back shoulder.
When he is releasing the ball the WR has Allen beat (frame 45)...Allen was technically beat at that point. That is when you can see Gabbert looking over to the single coverage. No need to go back shoulder with Troy Nolan all the way in the middle of the field and Allen already in an inside trail position.
Normally you'd go back shoulder when the CB is on top of the receiver and you want your guy to comeback for the ball.
I think Gabbert was just trying to throw the ball up to the guy who had a step on single coverage and he left the ball too short and too far inside.
A back shoulder throw typically is lower than that because if you put too much air under it you give the DB time to reach and make a play on the ball. There aren't a whole lot of QB's that execute the back shoulder throw well. It takes really good chemistry between the QB and receiver. Not very many QB even attempt it. How many times have we seen Schaub go back shoulder? And he's a pretty good QB. I don't see Gabbert as the type of QB that would try to do that at this stage in his career. That's a pretty high level throw, but it's very hard to stop if done correctly.
At first I thought it was a possibility that he was trying to go back shoulder, but after seeing the breakdown, I don't think he was.
JMO.
The way we saw the route suggests an out route.
The fade (forward) or back shoulder fade are simply variations of the out route.
When the receiver turns inside, it has to be a back shoulder fade at that depth (or most likely).
It's not any form of a come back or hook route, because the receiver never planned to do so, and the throw is too long to suggest such routes.
An acute "6 cut" requires the receiver to turn to the outside.
A stop route is not as viable as a back shoulder throw since the CB is right there on the inside hip of the receiver, even though this is still a possibility.
A stop route with the ball six inches to the outside and the receiver crowding the CB a little better could work.
But then again, it's hardly a different concept from a back shoulder fade.
IMO, Gabbert thought that Allen would continue on his run a little more before he can react back to the ball.
Either a stop route or a back shoulder fade here are viable.
Basically, a stop route with the throw at least 6" to the outside is a back shoulder fade.
With the room on the side line, a throw to the outside on the back shoulder is the best throw if a QB is to attempt a pass.
(By this, I mean more than 6 inches as Gabbert tried to sell us about the success of the play.)