If I were a GM, the first thing I do, even before I hire the head coach, is to find the best offensive line coach in the business and pay him whatever he wants.
Having wept my way through the long disaster of the Matt Millen years at the Lions, and the persistent disappointment of the Wayne Fontes years
WF's still the longest-serving head coach of the Lions, most victories, most defeats. I suspect that Dan Campbell will break the victories mark, but not the defeats mark. With the loss of both his coordinators to head coaching jobs, we'll find out soon enough -- he's got 24 already, 3–13–1,9–8,12–5).
A lot of teams fall into the habit of constant turnover in coaching, and stupid trades and drafts -- the Browns come to mind :^). Overpaying QBs, particularly with huge guaranteed money terms, trade approval, etc, will be the next thing to get its ass kicked.
Seeing the recent spate over overpaying non-QBs crazy guaranteed money suggests that the overpaying part will be with the NFL for a while yet.