As we head into this stretch towards the NFL playoffs, we still have a constant presence at the top of these rankings, as the top four teams remain unchanged from last week. But as has been the case all season, the mid-tier teams bring a lot of unknown and much excitement.

Unlike many other rankings across the internet, these are not some subjective rankings by a writer -- trust me, those would be way worse. Instead we use nERD, which is our calculation of how good a team really is, based on expected point differential against a league average team. If the team's nERD rating is 10, they would be expected to win by 10 points against a league-average opponent. Throughout the rankings we’ll also be using our Net Expected Points (NEP) metric, which is used as part of the nERD score. NEP measures the value of each play on the field based on how an average team would be expected to score in each scenario using historical data.

Each week, we’ll list all 32 teams from worst to best with a more detailed breakdown of five different teams. The highlighted teams will rotate each week, which will lead to each team being featured around three times during the course of the season.

32. San Francisco 49ers (nERD: -9.53, Record: 3-7, Last Week: 32)
31. Jacksonville Jaguars (nERD: -7.20, Record: 4-6, Last Week: 30)
30. Detroit Lions (nERD: -7.04, Record: 3-7, Last Week: 31)
29. Cleveland Browns (nERD: -6.42, Record: 2-8, Last Week: 29)
28. New Orleans Saints (nERD: -6.12, Record: 4-6, Last Week: 27)

By firing defensive coordinator Rob Ryan, New Orleans made their first move in trying to move forward into whatever the next era of the Saints might be.

Ryan brought life to the Saints in his first year as the defensive coordinator in 2013, but in the time since, the scheme has proved to be both too intricate and ineffective to keep any sustained success. Ryan’s defense was the worst defense in the league by Adjusted (for strength of schedule) Andre Roberts and with a safety trying to cover DeSean Jackson one-on-one down the field. Both scores came in the first quarter, and the offense struggled for the rest of the day. Overall, Washington ranks 18th in Adjusted NEP per play on offense, which comes from looking pretty good against bad defenses and pretty mediocre against good ones.

With a 24 percent chance of making the playoffs, there's still a possibility, especially with the string of defenses the team will play in the coming weeks. Only two, Philadelphia and Buffalo, are in the top 10 by Adjusted NEP per play, and they rank 9th and 10th.

Any playoff hope hinges on the result of this week’s game against the New York Giants. The Giants’ defense is 23rd in Adjusted NEP per play, but has the second best turnover rate in the league. Washington, on the other hand, turns the ball over the most of any team on offense -- 17.6 percent of drives.

19. Houston Texans (nERD: -1.05, Record: 5-5, Last Week: 19)
18. Indianapolis Colts (nERD: -0.99, Record: 5-5, Last Week: 18)
17. Philadelphia Eagles (nERD: -0.86, Record: 4-6, Last Week: 9)
16. Tampa Bay Buccaneers (nERD: -0.80, Record: 5-5, Last Week: 25)
15. St. Louis Rams (nERD: -0.66, Record: 4-6, Last Week: 16)
14. New York Giants (nERD: -0.37, Record: 5-5, Last Week: 17)
13. Minnesota Vikings (nERD: -0.10, Record: 7-3, Last Week: 15)
12. Atlanta Falcons (nERD: 0.51, Record: 6-4, Last Week: 14)

Just a month ago, the Falcons were 6-1 and looked to be in control of the NFC South. While we never fully bought into Atlanta being one of the best teams in the league -- they peaked at number eight in nERD rankings this season -- the schedule looked to favor them in the race against Carolina. But now the Falcons have lost three in a row against the Tampa Bay Buccaneers, San Francisco 49ers and a Matt Hasselbeck-led Indianapolis Colts. After looking like a shoo-in for at least a playoff spot, the Falcons now sit as the sixth-seed with a 54.6 percent chance of making the postseason.

Atlanta’s schedule, which was favorable to start the season, now looks like an uphill battle for a struggling team. The Falcons have to play the Vikings in Week 12, and now a game in Tampa Bay for Week 13 looks harder than it would have just a few weeks ago, before considering Tampa won the first matchup in Atlanta. The Falcons have to play the division leading Panthers twice in three weeks with a trip to Jacksonville in between.

Matt Ryan still ranks sixth among quarterbacks in Passing NEP per drop back, but his overall play has left much to be desired. The passing offense has understandably run through Julio Jones, but he’s been targeted so often and occasionally so inaccurately that Jones’ metrics don’t look like those of a great receiver -- Jones currently ranks 29th in Reception NEP per target among receivers who have seen the ball thrown their way at least 50 times this season. Jones ranks fourth among the six receivers who have seen 100 targets, and the two below him -- Brandon Marshall and Demaryius Thomas -- have dealt with much worse quarterback play this season.

11. Denver Broncos (nERD: 1.71, Record: 8-2, Last Week: 11)
10. New York Jets (nERD: 2.56, Record: 5-5, Last Week: 7)
9. Green Bay Packers (nERD: 2.72, Record: 7-3, Last Week: 13)
8. Buffalo Bills (nERD: 3.87, Record: 5-5, Last Week: 8)

In his time, Rex Ryan has not been a stranger to exotic defensive looks or blitzes. That’s exactly what he brought against the Patriots on Monday night, which allowed the Bills to stay close for most of the game. Buffalo was also one of the few teams to figure out a way to cover Rob Gronkowski, changing the coverage on the tight end just about every play. Gonk was covered by corners, safeties, linebackers, he was bumped at the line and he saw double coverage throughout the night. This is what Ryan is able to do and what was expected of him when he was brought in as the head coach.

The Bills have played fairly well for most of the season, outside of the games they were forced to start EJ Manuel. Tyrod Taylor has been slightly above average when he’s played this season -- he ranks 14th in Passing NEP per drop back -- which makes him the best quarterback the Bills have seen in quite some time. The shoulder injury suffered at the end of the Patriots game is concerning, but all indications point to him playing on Sunday. With his play at quarterback, the best rushing offense by Adjusted NEP per play and the 10th best defense by the same measure, the Bills are going to be a tough team to beat down the stretch.

Buffalo looked to be a playoff favorite, but with the loss to the Patriots and the surge from the Kansas City Chiefs, the Bills now look to be our seven seed by playoff odds with a 42 percent chance of making the playoffs, behind Kansas City and Pittsburgh. Those odds can shift greatly this week because the Bills will play the Chiefs on the road. We’re also high on the Chiefs -- 50.4 chance of a playoff berth -- but the winner of this game will have the inside edge of grabbing the six seed in the AFC this season.

7. Kansas City Chiefs (nERD: 4.31, Record: 5-5, Last Week: 10)
6. Seattle Seahawks (nERD: 5.29, Record: 5-5, Last Week: 6)
5. Cincinnati Bengals (nERD: 7.00, Record: 8-2, Last Week: 5)
4. Pittsburgh Steelers (nERD: 7.05, Record: 6-4, Last Week: 4)
3. Carolina Panthers (nERD: 9.94, Record: 10-0, Last Week: 3)
2. New England Patriots (nERD: 10.00, Record: 10-0, Last Week: 2)

The 2015 Patriots are not the 2007 Patriots, but that’s ok. They don’t have to be in order to go undefeated. For the record, the ‘07 Pats are our best team tracked by nERD since the 2000 season, and this year’s team isn’t even our top-ranked team in the league this season.

Still, New England has a decent chance of finishing the regular season at 16-0 again if they can get past the Denver Broncos this weekend. It will be an interesting matchup regardless of who is under center for the Broncos -- Brock Osweiler will literally be under center more than Peyton Manning would if he had played -- especially when the Patriots have the ball. New England currently ranks second on offense by Adjusted NEP per play, behind only Arizona, and Denver has the top defense in the league.

Tom Brady was slowed by the defense of the Bills last week, and he dropped to second among quarterbacks in Passing NEP per drop back behind Carson Palmer, though he’s still a leader for MVP consideration. Denver, with the ability to bring a pass rush along with stellar defensive back play, could similarly slow the quarterback down, though more often than not Brady has been able to adjust in the game and figure ways to counterattack aggressiveness from opposing defenses. Adjusting is what Brady has had to do much of this season, as he’s need out how to keep a high level of play while dealing with multiple injuries among skill position players, notably Dion Lewis and Julian Edelman.

It wouldn’t be surprising to see some dip in offensive efficiency for the Patriots over the next few weeks as they play around with lineups and figure out which offensive players and roles give them the best chance to win once the playoffs come. But with the Patriots, it also wouldn't be surprising if they figure that out without any dip in production at all.

1. Arizona Cardinals (nERD: 13.50, Record: 8-2, Last Week: 1)