You just made my point for me. It's a fumble, not a muffed backwards pass, because the throw backwards isn't considered a pass, it's considered a run. Therefore the player lost possession by an act other than passing. He fumbled a backwards throw. The very rulebook definition of a fumble. To muff it means the ball has already been fumbled and someone tries unsuccessfully to pick it up.
Wow he really threw his coaching staff under the bus with that last comment.
I think it's pretty much in a category with a muffed punt because it cannot be returned like a fumble if the defense recovers it. Unless the rules have changed, Hill can only get possession of a backwards pass and cannot advance the ball.
That's not the case anymore, Hill could've taken that thing all the way to the end zone. In fact, he returned it 21 yards according to the official game play-by-play, which is below.
Coleman, Tevin rush for loss of 14 yards to the MINN23, fumble by Coleman, Tevin recovered by MINN Hill, Aaron at MINN23, Hill, Aaron for 21 yards to the MINN44 (Coleman, Tevin).