Average nERD: -0.12 (35th)
Average Win Differential: 1.00 (28th)

Just because a coach’s name is featured on this list doesn’t mean they were necessarily always a one-dollar producer with a 10-dollar name. Bill Parcells was a legend while coaching the New York Giants in the late 1980’s and early 90’s, and he won two Super Bowls in that time. He also led the New England Patriots to Super Bowl XXXI, despite a loss and -- of course -- has a coaching tree that includes Bill Belichick, Sean Payton, Mike Zimmer, Todd Bowles, Tony Sparano, and Tom Coughlin, among many others.

But that doesn’t guarantee his tenure with the Dallas Cowboys in the early 00’s was much more than a simple exercise in mediocrity -- and unfortunately for him, our data at numberFire begins at 2000. Parcells oversaw the “just happy to be here, Clark” era of the Cowboys, from 2003 through 2006; prior to luring him out of retirement, the Cowboys had had three straight seasons of 5-11 football. Parcells’ Cowboys never finished better than second in the NFC East and only made two playoffs, losing in the first round both times. Even in his best season, the 10-6 showing in 2003, Dallas had an almost perfectly average 0.05 nERD, and in no season did he muster a mark above 5.00. Parcells may have developed quarterback Tony Romo into a Pro Bowler, but one player doesn’t make a legacy.