In 2013, the Bills introduced its 17th head coach in team history with the hiring of Doug Marrone. With Marrone, came long time assistant Donnie Henderson, who coached defensive backs while both men were at Syracuse University. Coach Henderson came to the Bills with 30 years of experience, coaching at both the collegiate and professional level. He is a highly respected coach and is considered one of the great teachers of the game, as he has been apart of some amazing defenses.

When coach Donnie, as the players like to call him, took over of the defensive backs in 2013; he took over a unit that was underwhelming at best. Statistics would show that the Bills had a pretty good pass defense. They were 9th in passing yards per game with 217. They were 6th in opponent competition percentage with 57%, and in the middle of the pack in quarterback rating at 84. However, all of these stats are misleading. Teams didn't need to pass on the Bills; the team was 31st against the run, giving up whopping 146 yards per game and 5.0 yards per carry. It was clear to the educated Bills fan knew the secondary needed some help.

If you remember, long-time veteran Leodis McKelvin was coming off a season when he was demoted to dime cornerback. Second-round pick Aaron Williams struggled at corner, forcing the new coaching staff to move him to safety. And new second-year cornerback Gilmore was okay but not great, coming off of his rookie season.

In my opinion, Coach Donnie single handedly revived the careers of both McKelvin and Williams, with both men scoring new contracts during his tenure. He was instrumental in safeties Jairus Byrd and Da'Norris Searcy scoring mega deals as free agents as well. He helped catapult Stephon Gilmore to shutdown status, and made cornerback Ronald Darby a legitimate rookie of the year candidate. Under coach Donnie, the Bills secondary was one of the best units in the NFL with young budding superstars primed for superstardom.

When coach Rex Ryan was hired in 2015, he retained the services of coach Donnie. Both men worked together while with the Jets, and from the outside looking in, it seemed like it'd be a perfect marriage. This offseason, coach Donnie left the team. It's still unclear what the reason for his departure was and if he left voluntarily or not. I'm not going to speculate, but I'm afraid fans are overlooking his departure. Losing an assistant coach that the players love and was productive under can be cataclysmic to the development of young players.

This situation is worth monitoring this season. The secondary is supposed to be one of the strongest units on the team, and in this defense the cornerbacks and safeties are what makes it work. Defensive backs coach Tim McDonald is still with the unit. Defensive coordinator Dennis Thurman will take over for coach Donnie. And the team hired Ed Reed to work with the safeties.

Did the Bills do enough? We'll soon find out.