It it was catchable wouldn’t that be a pretty workable definition of “ever so slightly behind him?” Are you really going to die on this hill? Nitpick Hill?
It was behind him as his momentum was going to the sideline and he twisted back for the ball. It was also thrown to the same side as the defender.
It would have been a very good catch given his full momentum going to the sideline. I would not expect Pettis, or anyone on the Bear except maybe Moody, to come up with it.
I would say the worst part of the throw is that he threw it inside where the defender was. He was open and if the ball is thrown to the sideline side it should have been a first down, though Pettis catching a ball is never guaranteed.
I would think JFC would want that one back. Throwing on the run obviously can be tough, especially where he had a limited window in which to throw given where the defender was. Hopefully he learns from it.