While some bell cows are fortunate enough to last an entire season, three others were forcibly removed from their posts by severe injuries and suspensions. These events led to opportunity for the player(s) behind them. We saw it with David Johnson to Kerwynn Williams, Ezekiel Elliott to Rod Smith and Alfred Morris, and Dalvin Cook to Jerick McKinnon and Latavius Murray

I know, I know -- you don’t need another reminder about how David Johnson suffered a season-ending wrist injury in Week 1 of 2017. And you probably have heard all you care to listen to about Zeke’s six-game suspension. But there are a couple of lessons here.

First, don’t forget how fragile the running back position is. Studies have proven that injuries are not predictable year over year on an individual player level. However, we do know that running back as a whole is a brutal position for injuries, especially for runners who get as much work as these bell cows. Each play carries with it a risk of injury. The more opportunities a running back sees, the more he puts he tempts his fate.

The second lesson to remember is to not draft handcuffs. David Johnson’s departure in Arizona led to a rotating door of running backs from Andre Ellington to Adrian Peterson to Kerwynn Williams, none of which offered predictable upside in this role in the preseason. You may remember that following DJ’s injury, Chris Johnson was signed to presumably take over that role, but he was severely outplayed by his teammates, including Andre Ellington. As soon as we grew used to Ellington’s pass-catching prowess, the team traded for Adrian Peterson and cut Chris Johnson. So if you drafted Adrian Peterson with the thoughts that he would soon enough be the featured back in Arizona, then props to you! Similarly, it was Rod Smith who outscored presumed backup Alfred Morris in four of the six games missed by Elliott in Dallas.

Lesson: We don’t know as much as we think we know regarding handcuffs. Often times, the presumed backup is never actually in the coaching staff's plans when injury falls upon a starting running back. There are likely better options to roster than a wishful stash on a murky depth chart. Running back is fragile.