Part of what made the Atlanta Falcons' historic Super Bowl loss to the New England Patriots as crushing as it was is the fact that this team was never able to get up off the mat. Once Kyle Shanahan left, Dan Quinn found it increasingly hard to replicate that level of offensive excellence.
The biggest problem Quinn made in replacing Shanahan as offensive coordinator was bringing in college coach Steve Sarkisian. Despite his quarterback background, Sarkisian oversaw a serious regression and was fired just two seasons later before retreating back to the collegiate level and eventually joining Texas as it's head coach.