First and foremost, it's Bowers himself. He had 2 years in the program. His star didn't rise. Perhaps it will at his next stop.
Also, we don't use the tight end a ton. It's hard to deny. Arod has liked the TE in the red zone in recent years but less so between the 20's.
There are two factors here:
1) Arod doesn't particularly love the intermediate middle, where tight ends often make their living. He seems to prefer the less congested areas, and hence, less risky areas of the field
2) Our very best playmakers have not been the TE's in recent years. When Bushman was our best weapon in the pass game, Bushman got the ball. When Dax, Allgeier, Puka and others (now Chase, Lassiter, Marion) were our best threats, they got the ball.
My hope is that Ryner Swanson comes back as 20-21 year old, in shape and physically mature version of himself, and he's featured in the O to great effect. Ditto for the 5-star kid we're recruiting now. I lay blame at the feet of both Arod and the Holkers for the way things went down, but notwithstanding that debacle, I want to think Arod is smart enough to tool his approach to his talent.