First, I haven't seen enough evidence to suggest Jarwin couldn't make 95% of the catches Witten makes. And really, much of Witt's catches are 3 to 4 yard gains, so even if Jarwin did drop most of those, it's not a heavy loss.
Nevertheless, I'm not ready to conclude that Jarwin can't catch 3- or 4-yard routes in traffic. And even if he can't at this point, he can definitely separate from defenders better than Witt, so maybe these catches won't always have to be so contested by the defender in the first place.
I simply think Jarwin needs more targets, ESPECIALLY on those play action passes to the TE, that are often small-ish gains with Witten in the flat, but could be bigger gains with a more athletic TE. And Jarwin certainly stretches the field better than Witten on the seam passes these days, because he gets into the 2nd level of defense much faster, opening up lanes for other WRs to sneak in behind his seam route.
And I LIKE Witt, he's been great. But at this point, I don't think he should be a primary read on many passing plays, he should be the outlet. And I believe Jarwin deserves some plays that are designed just for him, whether it's a sneaky TE screen, or a play action pass with a deeper route, where I know he'll be pretty open behind the TE because of team's respect for the running game.
I almost feel like it's a waste of a well-designed PA pass play only to throw it to Witt in the flat for 4 or 5 yards. It's hardly worth the deception, it's barely making the defense pay. Hec, with that, I'd still key on the run every play if I'm the defense if the threat is simply Witt for 4 yards in the flat. We can't get Coop or Gallup open on a deep out or in route for 15 or 20 yards? We can't get Jarwin open on a TE corner or seam route for 15 to 20 yards?
So, yes, I blame Moore for not using the personnel correctly, and for Dak not demanding in practice more out of the play action pass plays.
I don't blame Witt, he's giving us what he can. Jarwin can give us more on most of those pass plays, I do believe that. But if you need 3 or 4 yards near the goal line or on 4th and 3, I'm all for going with Witt in those critical situations as a primary read. Otherwise, we need the more athletic TE on the field more, and Witt (being the mentor I know he is), he can teach Jarwin how to block better.