Indeed, comparison with other opportunities is most important. I didn't make that clear. If you can do better teaching and/or better research outside the university, then go for it. (I am wrestling with this decision right now.) That would be a good reason to resign professorship, not the fact that a lot of university people are doing mediocre work.

My understanding, BTW, is that there is lots and lots of fantastic research being done in universities. You have to find it and hang around with the right crowd. Dr. Tarver's problem may simply be that he didn't find the opportunities.