Ranking the NFL's best and worst position groups

The Rams' and Saints' offenses are on fire. The Raiders' and Lions' defenses ... are not. But which position groups for those teams are the biggest strength -- and weakness?

Pro Football Focus ranks the NFL's 10 best and 10 worst position groups, starting with New Orleans' passing game -- which struggled uncharacteristically on Thursday night -- and ending with the Raiders' pass rush without Khalil Mack. PFF used its play-by-play grading and Wins Above Replacement model to help come up with the ranking, and all stats are from PFF and through Week 12.

Let's start with the best, and you can skip to the worst here.

Best position groups, from 1-10

1. New Orleans Saints passing game

The Saints put up a staggering 409 points through 11 games. A lot of that has to do with the well-oiled machine that is their passing attack, headed by an MVP-caliber season from Drew Brees. The quick passing game is their bread and butter, as no quarterback gets rid of the ball more quickly than Brees, who has an average time to throw of 2.45 seconds. No quarterback is better than Brees on those quick passes, either, as he has a league-high 94.9 passing grade and 81.9 percent completion on passes that come out in 2.5 seconds or less. In total, the Saints perform a successful early-down pass on 63.5 percent of their attempts, by far the highest percentage in the league.

2. Chicago Bears coverage unit

Defense is back in Chicago, led by one of the very best secondaries in the NFL. On the season, the Bears have allowed a league-low passer rating of 78.3 while being the only team in the NFL to intercept more passes than the number of touchdowns it has allowed through the air. When quarterbacks have attempted passes 20 or more yards downfield against the Bears, just 10 of 37 have been completed, with twice as many interceptions as touchdowns allowed (six to three). Chicago allows -0.07 expected points added on early-down passes, meaning its opponents lose points on early-down pass attempts.