In case you missed it, be sure to check out Warren Sharp's fascinating statistical breakdown of how former Buffalo Bills head coach Doug Marrone possibly derailed the development of quarterback E.J. Manuel in FoxSports.com.
In sum, Marrone became painfully predictable on first down with the 2013 first-round pick.
Manuel posted the fourth-best passer rating ever for a rookie in Weeks 1-3, particularly excelling on first down, and then Marrone decided to run... and run... and run some more on first down. As Sharp breaks down, Marrone called pass plays 45% of the time on first down in Manuel's first three starts in 2013, and then 20% his next two starts (nine passes and 36 runs).
The rest of his rookie season, Manuel handed the ball off more than 70% of the time on first down in 1-score games.
Which of course means that Manuel was often passing the ball when the defense was ready for it. Opportunities to burn defenses in 1-on-1 coverage deep on early downs was rare. And such unimaginative play-calling became a factor in a rocky first two seasons for Manuel.
The trend continued into 2014 with Manuel, Marrone turned to Kyle Orton after four games and Manuel didn't throw a pass the rest of the season.
All of this despite the fact that Manuel had a 98 passer rating on first and 10's his first three starts as a NFL quarterback.
Read the story linked above for the full breakdown. It's worth your time. Of course, the tape doesn't lie --- Manuel has struggled for stretches and must impress this summer to stay on the roster. But probably nobody is happier to work with a different coaching staff.