There are currently 10 coaches that have coached the same team for the past five years and are still there this coming year. I included Sean Payton of the Saints in this group, even though he was suspended one of those years.
A huge problem for the rest of the coaching brotherhood is the league has become a win now or be out of a job league. I know, that's not covering any new group. But owners are not going to let coaches keep losing and keep their jobs. Including the past 5 seasons and this upcoming season, here's how many coaches each franchise has had in that time:
5 coaches: BUF
4 coaches: CLE, PHI, SFO
3 coaches: CHI, DEN, HOU, JAX, LAR, MIA, OAK, SDC, TBB, TEN
2 coaches: ARI, ATL, DET, KCC, MIN, NYG, NYJ, WAS
Essentially, 14 teams have had 3 or more coaches over 5 full years and the upcoming season. So, sure, in theory teams should not be tempted to jump at any Tom, ****, or Harry that comes along at QB, and they probably could be better suited to invest their draft picks and cap dollars elsewhere, coaches have to take way more chances to find a QB or they flat out will not have a job. It's that simple. Gone are the days when a coach could get 5 years to build a team and a system. It would be great if owners let coaches try to really build a team properly, but that went out with black and white tv.