Week 15 NFL Power Rankings: Biggest breakthroughs -- including a new No. 1

Clark says Eagles still 'very formidable' in playoffs (1:18)

Ryan Clark explains why the loss of Carson Wentz doesn't derail the Eagles' postseason hopes with QB Nick Foles taking over. (1:18)

The final stretch of the regular season offers as good a time as any for reflection.

Here's a rundown of the Week 15 Power Rankings, as voted on by our power panel -- a group of more than 80 writers, editors and TV personalities -- with a look at some of the most notable statistical breakthroughs across the league.

ESPN Stats & Information's John McTigue contributed the following information.

Methodology: These rankings are based on which teams voters think would win head-to-head matchups. Higher-ranked teams would be favored against lower-ranked teams. Coming off a win doesn't guarantee a jump, and a loss doesn't guarantee a fall.

Previous rankings: Week 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | Preseason

1. Pittsburgh Steelers

2017 record: 11-2
Week 14 ranking: No. 5

The Steelers have more sacks in 13 games this season (41) than they did in all of 2016 (38). Part of that is Cameron Heyward recording a career-high 9.0 sacks. Another is T.J. Watt recording the most sacks (6.0) by a Steelers rookie since Kendrell Bell in 2001.

2. New England Patriots

2017 record: 10-3
Week 14 ranking: No. 1

The Patriots' defense had a major turnaround following a 2-2 start to the season. Through Week 4, they had allowed the second-most points per game in the NFL (32.0). They've allowed an NFL-best 13.5 points per game since, with Monday night's 27-20 loss to Miami being the only time the unit has allowed even 20 points in their past nine games.

3. Philadelphia Eagles

2017 record: 11-2
Week 14 ranking: No. 2

Carson Wentz's season came to an abrupt end when he tore his left ACL in Sunday's win over the Rams, but what he accomplished this year was stellar. Wentz currently leads the NFL in passing touchdowns and set a franchise record for touchdown passes in a single season (33).

4. Los Angeles Rams

2017 record: 9-4
Week 14 ranking: No. 4

The Rams averaged 14.0 points per game in 2016. This year they are averaging more than twice that (30.5). Jared Goff's improvement has been notable, but Todd Gurley II has been the catalyst. He has accounted for 34 percent of the team's yards from scrimmage, highest in the NFL.

5. Minnesota Vikings

2017 record: 10-3
Week 14 ranking: No. 3

There's no bigger breakthrough for the 2017 Vikings than Case Keenum. Even after Sunday's loss to the Panthers, Keenum still ranks third leaguewide in Total QBR and has led Minnesota to an 8-3 record in his starts. He entered the season with a career 9-15 record as a starter.

6. New Orleans Saints

2017 record: 9-4
Week 14 ranking: No. 7

The Saints' running game has been a revelation this season, with both Alvin Kamara and Mark Ingram ranking in the top five for yards per rush. As a team, they have 19 rushing touchdowns, their most since the 2009 Super Bowl season (21).

7. Carolina Panthers

2017 record: 9-4
Week 14 ranking: No. 9

Cam Newton has more completions to Christian McCaffrey this season (67) than he has ever had to Panthers running backs in a single season. McCaffrey leads the team and all rookies in receptions.

8. Jacksonville Jaguars

2017 record: 9-4
Week 14 ranking: No. 8

The Jaguars are allowing nearly 10 points fewer per game than they did last season, and currently boast the league's best defense in terms of points allowed, takeaways and Total QBR. Last season they ranked 25th in points allowed, 30th in takeaways and 14th in opponent QBR.

9. Seattle Seahawks

2017 record: 8-5
Week 14 ranking: No. 6

Richard Sherman, Kam Chancellor and Earl Thomas all have missed multiple games this season, but what has to be encouraging for Seattle is how the team has handled it. With any of those players off field this season the Seahawks have allowed a 39 Total QBR, which is better than their QBR allowed for the entire season (42).

10. Atlanta Falcons

2017 record: 8-5
Week 14 ranking: No. 10

The Falcons' pass rush was dependent on Vic Beasley Jr. last year, but others are getting more involved, which has resulted in a sack rate up nearly two full percentage points from 2016. Most notable is veteran Adrian Clayborn, who at 29 years old has set a career high with 9.0 sacks.

11. Los Angeles Chargers

2017 record: 7-6
Week 14 ranking: No. 11

The Chargers have a winning record despite an 0-4 start thanks to takeaways and giveaways. Philip Rivers has the lowest interception percentage of his career, Melvin Gordon has the most touches without a fumble (272) and the defense has 20 takeaways since the start of Week 5, tied for most in the NFL.

12. Baltimore Ravens

2017 record: 7-6
Week 14 ranking: No. 13

Alex Collins was cut by the Seahawks on Sept. 2 and signed by the Ravens on Sept. 5. Flash forward to December and he's fourth in the NFL in yards per rush (5.1) and just 175 yards shy of his first 1,000-yard season.

13. Kansas City Chiefs

2017 record: 7-6
Week 14 ranking: No. 18

The Chiefs' big-play offense being led by Alex Smith is probably a surprise to most. Smith has 11 completions and eight touchdowns of at least 40 yards this season, which are both career bests. He had 10 touchdowns of at least 40 yards his first four seasons with the Chiefs.

14. Green Bay Packers

2017 record: 7-6
Week 14 ranking: No. 16

The Packers' running back situation was up in the air entering the season, but now they have several strong options. Rookie Aaron Jones has a pair of 100-yard rushing games, and rookie Jamaal Williams has five touchdowns and is averaging 125.3 scrimmage yards in his past three games.

15. Dallas Cowboys

2017 record: 7-6
Week 14 ranking: No. 14

DeMarcus Lawrence's emergence has been one of the biggest breakthroughs for the Cowboys. His 13.5 sacks this season are second-most in the NFL and most by a Cowboy since DeMarcus Ware had 19.5 in 2011. Lawrence entered the season with 9.0 sacks in 32 career games.

16. Detroit Lions

2017 record: 7-6
Week 14 ranking: No. 21

The Lions allowed the worst completion percentage in NFL history last season (73 percent). They're allowing a 63.9 completion percentage this year, which ranks 23rd in the NFL, but the improvement is significant.

17. Buffalo Bills

2017 record: 7-6
Week 14 ranking: No. 17

The Bills lost their leading tackler (Zach Brown) and three of their top defensive backs -- Stephon Gilmore, Ronald Darby and Nickell Robey-Coleman -- this offseason. Despite that, they've allowed fewer points per game and are forcing turnovers at a higher clip than last year.

18. Tennessee Titans

2017 record: 8-5
Week 14 ranking: No. 12

The Titans' defense has shown improvement thanks to some playmakers in the secondary. Kevin Byard is tied for the league lead in interceptions (six) and both Adoree' Jackson and Logan Ryan already have more pass breakups than any Titans defender did last season.

19. Oakland Raiders

2017 record: 6-7
Week 14 ranking: No. 15

Not a lot of breakthrough performances for the Raiders this season, but they do have one player who has had no problem literally breaking through. Marshawn Lynch, after missing a year, is averaging 2.4 yards per rush after contact, which would be the second-best rate of his career.

20. Arizona Cardinals

2017 record: 6-7
Week 14 ranking: No. 23

It might be a stretch to call Chandler Jones a breakthrough considering he has had three other 10-sack seasons. But Jones already has a career-high 14.0 sacks and leads the NFL, something no Cardinal has done across an entire season.

21. Washington Redskins

2017 record: 5-8
Week 14 ranking: No. 22

Prior to his injury, Chris Thompson was the biggest highlight of Washington's season. Thompson was on pace for nearly 1,300 scrimmage yards and through Week 11, his last game of the season, he led all running backs in receiving yards.

22. Miami Dolphins

2017 record: 6-7
Week 14 ranking: No. 24

Kenyan Drake is showing why the Dolphins were willing to deal Jay Ajayi at the trade deadline. Drake has rushed for 100 yards in back-to-back games and accumulated an NFL-best 334 scrimmage yards in the past two weeks.

23. Cincinnati Bengals

2017 record: 5-8
Week 14 ranking: No. 19

It's rare for Bengals rookies to play in recent years, let alone make an impact, but that's exactly what Carl Lawson is doing. Lawson is the team leader in sacks (7.5) and the first Bengals defensive rookie to play 300 snaps since Vontaze Burfict in 2012.

24. Denver Broncos

2017 record: 4-9
Week 14 ranking: No. 27

This season has been a letdown for Denver, but the best thing to come out of it is the emergence of rookie left tackle Garett Bolles. He has played the most snaps of any left tackle this season, and the Broncos are averaging more yards per rush and allowing less pressure than they did last season.

25. Houston Texans

2017 record: 4-9
Week 14 ranking: No. 25

DeAndre Hopkins has had big seasons before, but his 2017 campaign could top them all. He leads all players with 11 receiving touchdowns and he's second in receiving yards (1,233). And in what has been a running theme for his career, he has caught multiple touchdowns from three different quarterbacks this season.

26. Chicago Bears

2017 record: 4-9
Week 14 ranking: No. 29

Mitchell Trubisky is developing, and it helps that he has a duo of running backs making plays for him. Jordan Howard has rushed for 1,000 yards for the second straight season while rookie Tarik Cohen leads the team in 20-yard plays.

27. Tampa Bay Buccaneers

2017 record: 4-9
Week 14 ranking: No. 26

Rookie tight end O.J. Howard has only 25 receptions this season, but he has still found the end zone five times for the second-most receiving touchdowns on the team. Howard and Cameron Brate have led the Bucs to the second-most touchdowns by tight ends this season.

28. New York Jets

2017 record: 5-8
Week 14 ranking: No. 20

After losing Brandon Marshall and Eric Decker, the Jets' receiving corps was supposed to be one of the worst in the NFL, but Robby Anderson had other ideas. Anderson is 152 yards shy of 1,000 for the season, and his six touchdowns of at least 20 air yards are most in the NFL.

29. San Francisco 49ers

2017 record: 3-10
Week 14 ranking: No. 28

The quarterback position was looking like a major weakness for the 49ers, but the trade for Jimmy Garoppolo may have solved that. Garoppolo is 2-0 with a 66 Total QBR for San Francisco. The 49ers' other starting quarterbacks went 1-10 with a combined 29 Total QBR.

30. Indianapolis Colts

2017 record: 3-10
Week 14 ranking: No. 30

One of the few bright spots for the Colts is tight end Jack Doyle, who has caught 64 passes, second most among tight ends behind only Travis Kelce. Doyle could have an even bigger impact next season with Andrew Luck back under center.

31. New York Giants

2017 record: 2-11
Week 14 ranking: No. 31

The Giants have had some issues, but the good news is that some other pass-catchers are getting work with Odell Beckham Jr. and Brandon Marshall out. Sterling Shepard has caught 73 percent of his targets, and rookie tight end Evan Engram is just the fourth Giants rookie to catch at least 50 passes in a season.

32. Cleveland Browns

2017 record: 0-13
Week 14 ranking: No. 32

The Browns are winless, but there have been some bright spots, and nothing is more encouraging than the rushing defense. They've allowed 3.3 yards per rush, the fewest in the NFL this season and a massive improvement over last season, when they ranked 29th.