By MARK SIMON & ALEX VIGDERMAN

Aaron Rodgers’ rough game last Sunday was a costly one in the World’s No. 1 Quarterback Rankings.

Rodgers, who had the slimmest of leads on Patrick Mahomes, fell two spots, not just behind Mahomes, but behind Tom Brady as well. His -9.5 Points Above Average in Week 1 were 17 fewer than Mahomes, so the Chiefs quarterback now has a sizable edge on his Buccaneers and Packers counterparts.

A reminder that The World’s No. 1 Quarterback Ranking is based on a model devised by Bill James to evaluate The World’s No. 1 Starting Pitcher. Bill’s model was based on cumulative evaluation of individual starts over an extended time period using the metric Game Score.

The World’s No. 1 Quarterback Ranking uses our player value stat Total Points to make a cumulative evaluation of game performance over a three-year period. The key to our calculation is PAA, which as we previously noted is the statistical underpinning of Total Points that is centered at zero so that positive numbers are above average and negative numbers are below average.

Success over time is key to maintaining a good ranking. Prolonged inactivity results in a ranking drop. The most recent performances carry the most weight.

The current Top 8 are

1. Patrick Mahomes (up by 1)
2. Tom Brady (up by 1)
3. Aaron Rodgers (down by 2)
4. Deshaun Watson
5. Russell Wilson
6. Josh Allen
7. Derek Carr
8. Kirk Cousins (up by 1)

The top PAA performers in Week 1 are not in that group. They were a couple of unexpected names, Teddy Bridgewater and Tyrod Taylor. Bridgewater’s 9.1 PAA bumped him up five spots, from No. 20 to No. 15.

Taylor’s climb was a bigger one, from No. 58 to No. 22 after a huge game against the Jaguars. Others with similar jumps included Jameis Winston (from No. 57 to No. 26 after outplaying Aaron Rodgers) and Jalen Hurts (No. 72 to No. 32 after beating the Falcons).

Bridgewater’s Week 1 win against the Giants came in a game in which he completed 28-of-36 passes for 264 yards and two touchdowns. Bridgewater totaled two touchdown passes in his last five starts in 2020.

As was discussed on the Off the Charts podcast, Bridgewater succeeded largely by being a game manager, but picking his spots when he needed. He was the top PAA quarterback for the week in passes 11 to 15 yards downfield, completing 5-of-5 for 87 yards.

Taylor, in for Deshaun Watson, overshadowed Jaguars rookie Trevor Lawrence, who was making his NFL debut. Taylor looked like an experienced vet, completing 21-of-33 passes for nearly 300 yards and two scores. His season debut went a lot better than his 2020 debut for the Chargers, in which he went 16-for-30, broke two ribs, and didn’t throw another pass the rest of the season. Meanwhile, Lawrence finished with -4.4 PAA.

Winston threw for only 148 yards but had five touchdowns in a surprisingly dominant showing against the Packers. He finished drives effectively with short passes, going 5-for-5 with four touchdown passes on plays inside the 10, avoiding the interception issues that previously cost him.

Rodgers, Ben Roethlisberger, and Jets rookie Zach Wilson all had -9.5 PAA. But two quarterbacks were worse: Ryan Tannehill and Andy Dalton.

Tannehill’s -17.2 PAA cost him considerably. He fell 9 spots in the rankings, from No. 8 to No. 17 after being sacked six times in a loss to the Cardinals. He now faces the Seahawks in Week 2. Dalton dropped 26 spots, from No. 49 to No. 75, after posting -10.7 PAA in his Bears debut. Dalton’s showing was actually worse than his 2020 season-ender against the Giants, when he totaled -8.0 PAA.

Here are the rankings through Week 1.