ESPN's NFL Football Power Index rankings for Dec. 8

There’s a new No. 1 in ESPN’s NFL Football Power Index.

After the New England Patriots’ second loss in succession and the Arizona Cardinals’ sixth consecutive win, the Cardinals leapfrogged the Patriots into No. 1 in FPI after Week 13.

The Patriots had been No. 1 in FPI every week since the conclusion of Week 4 through the end of Week 12.

The Cardinals' FPI rating improved by 1.2 points to 8.7, meaning they are projected to be nearly nine points better than an average NFL team on a neutral field.

The Cardinals rank second in the NFL in offensive FPI, but they are coming off their second-best defensive performance of the season. They had a defensive efficiency of 93 (on a 0-to-100 scale) in their 27-3 victory over the Rams on Sunday. Their best defensive performance came in their 47-7 win over the 49ers in Week 3, when they had an efficiency of 100.

The Patriots dropped 0.4 points in their FPI rating to 7.6. The No. 3 Seahawks and the No. 4 Bengals both gained more than a point in their FPI rating and are within a half-point of the Patriots.

Although the Panthers remained unbeaten, their FPI rating declined by 0.2 points, and they dropped two spots in the rankings to fifth. The Panthers' defensive efficiency of 25 against the Saints on Sunday was their worst of the season.

Among Week 14 games, the Steelers’ game at the Bengals has the highest matchup quality: 87 on a 0-to-100 scale.

The chart above shows the ESPN Football Power Index rankings for Dec. 8, after Week 13 of the 2015 NFL season. For a full explanation of how the FPI is put together, please read this explainer. For more background, you also can read this Q&A.