As passing numbers continue to inflate across the NFL, it's becoming more and more difficult to correctly assess even basic measurements of pass production. A 65% completion rate sounds exceptional, right? Well, 18 different quarterbacks exceeded that benchmark over 10 or more starts in 2018. And as quarterbacks such as Jared Goff and Ryan Fitzpatrick seem to transform into completely different players with new coaches and in new situations, it's becoming clear that the traditional measurements fall far short in their mission to accurately and comprehensively identify the best and worst quarterbacks.
ESPN Stats & Information offers a different approach to evaluation, calculating the expected points added by every play based on its start and end state in terms of factors such as down and distance, field position and time remaining. Successful and unsuccessful plays come from the combined efforts of every player on offense and defense as well as coaches, but the EPA can be stretched to evaluate quarterbacks by comparing the EPA totals of plays in which they pass or run the ball with the EPA totals of plays without their involvement -- typically runs, defensive plays, and special-teams plays. That creates an imperfect evaluation because quarterbacks do not have full control over the success or failure of their attempts, but it does a much better job of divorcing a quarterback's responsibilities from those of his supporting cast than either basic passing statistics or won-lost records could hope to do.
By comparing the total EPA of each quarterback's attempts to that of his team's running game, defense and special teams, we have identified the top 10 and bottom 10 signal-callers in added value for 2018. Note that this is different from the most valuable quarterbacks by total value. For example, Tom Brady is seventh in QB EPA (+97.6), but he doesn't make our list because the rest of the Patriots' roster also had plenty of value by expected points added.
Read through our various categories of passers, or skip ahead to the metric of your choice here:
Note: We included only quarterbacks who made 10 or more starts in 2018, which excluded QBs from three teams (the 49ers, Buccaneers and Ravens).
QB EPA: +219.4 (1st)
Team EPA: -74.4 (20th)
QB-added value: +293.4
There wasn't much mystery to which player would land at No. 1. You'd be hard-pressed to come up with any measurement of player value that didn't have Patrick Mahomes at the top of its list in 2018. He was one of just two quarterbacks with 5,000 passing yards and the only one with 50 passing touchdowns. Those season totals would have propelled him to his standing however he accumulated them, but he epitomized the added-value concept by having his best production in the Chiefs' four losses, in which he averaged 337 passing yards, 3.75 passing touchdowns and a 111.8 quarterback rating. When the team lost, it clearly did so despite Mahomes' brilliance. And the Chiefs would have lost many more games without him, thanks to the league's seventh-worst defense by DVOA.