How about out of match form & match confidence ? He's been out for five months. Coming back from that to a 14 minutes EPL debut (actually, a debut in any European top flight league for him) isn't a guarantee he'll have instant impact, especially since he didn't really get service during those 14 mins he played. So the following game (Liverpool) he doesn't come on. Then he makes his 2nd EPL appearence with Hull 0-2 down to the league leaders, playing away, 17 minutes to go. Can't hold up a couple of high balls he should have done much better with for sure, but does make a nice run with the ball at one point. In the end, no impact... The following game, he's out of the 18 !! I don't think that can help the confidence much.
I don't mean by this that he's being treated unfairly because that's just the nature of squads and lineups, it's just competitive. All I'm saying is if Gedo doesn't show you guys enough positive signs yet, it's not that surprising to be honest. That is until he gets one or two proper chances. You know... the kind that some other striker in the team keeps getting right now as a result of existing.