Sometimes scheme is the number one reason why players lack production. For example, OJ Howard at Bama has everything a TE is supposed to have. But his production has basically been non-existent in his career at Bama (with the Clemson game excepted) because of what he is asked to do. He's asked to block, and he's almost never the primary option on passing plays in favor of their typically dominant WRs.
So you always have to ask yourself how much of the problem is utilization and how much of the problem is talent? With Koyack, I think he was just disappointingly not that talented. And last year, I think once Smythe went down they just said "look... we have CJ Prosise, Will Fuller, etc. let's get the ball in the hands of our best players." So we don't really know what we have or don't have with Smythe/Weishar.
I do know that in Weishar's case the problem was that he wasn't strong/big enough when he arrived to play the position, and then he apparently put on bad weight. So he had one year of scout team duty while getting bigger, and then last year he was always supposed to be an afterthought... and he was ill-suited to be either the primary blocking or receiving TE. It's totally reasonable that he could as an upperclassman be in correct shape and ready to be a very productive player.
