Here is the disconnect. You claim that tight ends lack value because not many work out. Tight ends have tremendous value because it is a very difficult position to play well and requires a rare blend of attributes; size, strength, speed, agility, quicks, smarts. If you have a good one, they are gold.
Secondly, Hockenson was a very productive receiver. To diminish his role in the offense because they weren't winning is disingenuous. I believe he had some issues with blocking, focus and route running that soured Detroit on him, but if you think the current trio is in any way, shape or form an equal talent replacement for Hockenson, much less a potentially more balanced top tight end, then I question your judgement.