I'm not sure how typical it is or isn't. Off the top of my head I can think of a number of coaches with more success the 2nd time around. Belicheck, Levy, Carroll, Rivera, probably quite a few that flamed out after success. I think it all comes down to good timing, Marv was the right coach at the right time for the Bills, I would think with a strong offense, being a good coach, Ryan could be the right coach at the right time.