Yards after catch is almost exclusively dependent on where the qb is placing the ball.
If your reciever has to make adjustments just to make a completion, he's not afforded the opportunity to make adjustments for extra yardage.
Tua is dink and dunk and only knows how to hit a reciever on a stop route after he's open instead of leading him into the catch.
The problems Tua is having does not fall on anyone except Tua. There are multiple targets on every play, but throwing to the checkdown each time is a choice.
Fitzpatrick doesn't have these problems with the same supporting cast.
You can teach a quarterback a playbook, and a smart quarterback can use that knowledge to audible into an ideal play. However, just like speed, you can't teach field vision. You either have it or you don't. Tua doesn't.