He's a big guy that has pushed through a lot of injuries. You are right though, he isn't a down the field speedy threat and there were continuous failed down the field attempts to him, that he failed to get there fast enough. He wasn't over thrown, is was slow to get there. This isn't a knock on him, it's a knock of the staff for putting him in a bad position.
There were 2 or 3 other WR that should have been the ones running the go routes, not him. He is a tough dude that gets tough yards and should have been utilized in the slot. There's a misconception that the slot guy has to be smaller and faster. Screw that, put a hoss in there like Bru and dare a defender to defend him in the flat or over the shallow middle. He should have been the go to routinely for short yardage plays and 3rd downs when the Vols needed to move the chains. Imagine going two TE and having Bru in the slot. Basically unstoppable. They just weren't creative enough at putting the best talent in the best positions to win one on ones, or exploit zone defenses.