How ironic you should mention Reggie. Harrell is the only guy, at Tennessee, to wear #92 since gave Reggie White. Harrell was very highly respected as a hard worker, played through a lot of pain, and was a team leader. I don't fault TT at all for taking the chance on him - he has the potential to be great. Too bad it hasn't worked out.
Was Adrianne Peterson a bad pick for Minny? He had a more troubling injury history, yet Minny took a chance and reaped the benefits. It hasn't worked out for Justin yet, and I am hopeful that it will. If Justin had back trouble in college and that continued in the NFL, then I would fault TT. The fact is, he had a bicep tear, and the injury in the NFL was a back injury when he was lifting too much weight.
As far as TT replacing his own players now that Sherm's guys are mostly gone - of course he is. I think he would upgrade at QB and trade AR if it was possible. TT has shown he is not afraid to make the tough choice and to cut a pick early that proves to be a mistake (Brohm). I suspect TT looks at every single position as a possibility for improvement. As far as Matthews replacing AJ and BJ replacing Harrell as some admission of failure - we need more LBs and DLs than just one