Vikings quarterback Sam Bradford set a new NFL record for completion percentage this season, completing 71.6 percent of his passes. Which serves as a good reminder of how meaningless a statistic completion percentage can be.
The problem with completion percentage is that it treats all completions equally, which is obviously ridiculous: A completion for zero yards doesn’t help a team any more than an incompletion. A completion short of the line to gain on third down doesn’t help much more than an incompletion, either. And Bradford had a lot of those short completions that didn’t pick up first downs.
How many? While setting the NFL record for completion percentage, Bradford finished 17th in the NFL in first down percentage, among the 33 quarterbacks who threw at least 200 passes.
Bradford completed so many passes short of the line to gain that he got a first down on just 35.7 percent of his passes. Half the quarterbacks in the league picked up a first down on a higher percentage of their passes, even though none completed as high a percentage of his passes.
Consider, for instance, Falcons quarterback Matt Ryan: Although Ryan completed 22 fewer passes than Bradford this season, Ryan picked up 41 more first downs than Bradford. There were eight quarterbacks in the NFL who threw for more first downs while completing fewer passes than Bradford.
Bradford’s season points to one of the flaws of the NFL’s official passer rating statistic, which incorporates completion percentage but not first downs. Bradford finished sixth in the NFL in passer rating, thanks in large part to that record first down percentage. Statistics that factor in not just whether a pass was completed but whether that pass picked up a first down, like ESPN’s QBR or Football Outsiders’ DVOA, didn’t think so highly of Bradford: He finished 18th of 30 qualifying quarterbacks in QBR and 17th of 34 qualifying quarterbacks in DVOA.
Vikings coach Mike Zimmer has declared that Bradford earned the right to start next season. If Zimmer wants to win with Bradford next season, he’s going to need Bradford to start pushing the ball down the field.