Nick Foles is not the quarterback Carson Wentz is. (Elsa/Getty Images)

The quest for a championship ring starts Saturday and, as the NFL postseason opens, the Philadelphia Eagles are the No. 1 seed in the NFC for the first time since 2004, the year they last made a Super Bowl appearance.

The Eagles looked strong for most of the season, and Coach Doug Pederson saw his team win 13 games despite losing quarterback Carson Wentz to a season-ending knee injury in Week 14. Backup Nick Foles wasn’t a disaster in relief but only completed 56 percent of his passes, producing 4.8 adjusted net yards per attempt, a tweak on yards per attempt that gives quarterbacks credit for throwing touchdowns and penalizes them for interceptions and sacks. Wentz, however, produced 7.4 adjusted net yards per attempt under center, a huge difference for a team with championship aspirations.

Since 2002, the year the league expanded to 32 teams, just one eventual Super Bowl winner, the 2007 New York Giants (4.4 ANY/A), had a lower adjusted net yards per attempt than the Eagles did with Foles during the regular season.

In addition, the Eagles offense with Wentz under center scored 7.9 more points per game than expected via the pass after you account for the down, distance and field position at the time of each throw. With Foles, they scored 7.4 points per game fewer than expected. Only the 2007 Giants and 2015 Denver Broncos won the Super Bowl with their passing game scoring fewer points than expected, but neither of those teams was worse than minus-1.3 points per game below expectations.

Having Foles under center almost certainly will be the factor that bounces the Eagles from the playoffs. Here are the fatal flaws for the rest of the teams in the playoffs:

NFC

Minnesota Vikings (13-3) | NFC No. 2 seed

Before this season, Vikings quarterback Case Keenum had played 26 games with two teams in three cities, managing just 5.4 adjusted net yards per attempt and a 78.4 passer rating. This year, he set career highs in both metrics (7.0 and 98.3, respectively) with good enough play to be ranked as the second-most valuable passer in the NFL this year per ESPN’s Total Quarterback Rating.

Yet his performance against teams that ranked in the top 10 of Football Outsiders’ Defense-adjusted Value Over Average pass-defense rankings, which measures a team’s efficiency by comparing success on every play to a league average based on situation and opponent, were significantly worse than those games against teams outside the top 10 — bad news for a team that may have to play the Los Angeles Rams (No. 3 in pass defense DVOA), the Eagles (No. 7), the New Orleans Saints (No. 5) and/or the Carolina Panthers (No. 10) en route to a Super Bowl appearance.

Case Keenum in 2017 Games Att Comp Comp% Yards Yds/Att TD INT Passer rating
vs. top 10 pass-defense DVOA 5 179 115 64% 1,219 6.8 7 5 85.4
vs. all others 9 302 210 70% 2,328 7.7 15 2 105.9

Los Angeles Rams (11-5) | NFC No. 3 seed

The Rams are full of youth and exuberance but low on experience. And that could be an issue.

Heading into the season, the Rams were the youngest team in the NFC, averaging 25.1 years of age. The Seattle Seahawks won a championship in 2013 with the fourth-youngest roster (25.3), but since then more seasoned teams have been the last team standing.

Super Bowl winner Average age (in years) Rank
2013 Seahawks 25.3 4th youngest
2014 Patriots 25.8 11th
2015 Broncos 26.2 18th
2016 Patriots 26.1 15th

Plus, rookie coaches like Sean McVay don’t typically fare well in the Super Bowl. Just two have managed to hoist the Vince Lombardi Trophy in their debut season: Don McCafferty (1970 Baltimore Colts) and George Seifert (1989 San Francisco 49ers).

New Orleans Saints (11-5) | NFC No. 4 seed

The Saints’ defense is much improved, despite the fact that they surrendered 69 plays of 20 or more yards, highest among the playoff teams. The most big plays given up by a Super Bowl winner since 2002 was 71 by the 2011 Giants. The 2014 Patriots are next with 64.

But 19 of those big plays came during the first two weeks, when the Saints’ defense looked markedly worse. And 15 others came during games in which rookie cornerback Marshon Lattimore — the ninth-best at the position in 2017, per the game charters at Pro Football Focus — was injured. In other words, it’s hard to find a fatal flaw for New Orleans as the Saints seek their second championship ring in franchise history.

Carolina Panthers (11-5) | NFC No. 5 seed

The Panthers allowed 4.0 yards per carry but were extremely vulnerable once an opposing running back got beyond the line of scrimmage. Carolina surrendered 1.11 second-level yards per carry (yards earned by opposing running backs against a team five to 10 yards past the line of scrimmage) and 0.94 yards per carry in the open field (more than 10 yards past the line of scrimmage), ranking them No. 18 and No. 27, respectively, in the NFL. Since 2002, only the 2006 Indianapolis Colts managed to win the Super Bowl while being below average (ranked No. 16 or worse) in both categories.

Atlanta Falcons (10-6) | NFC No. 6 seed

The Falcons’ defense ranks 22nd in DVOA. The only time a Super Bowl champ was ranked this low or lower by this metric was when the Indianapolis Colts (No. 26) won it all in 2006.

Indianapolis had Pro Bowl quarterback Peyton Manning, the No. 1 passer per QBR (86.4), that year. Atlanta has Matt Ryan (64.2 QBR), who ranks fifth. It may not sound like a large gap, but consider the Colts produced 12.1 more points per game than expected via the pass with Manning in 2006 compared to the Falcons scoring 6.6 more points per game than expected with Ryan this past season.

AFC

New England Patriots (13-3) | AFC No. 1 seed

Since 2002, 22 of the past 30 Super Bowl participants had a net passer rating differential among the top five in the league, including 10 of the past 15 winners. The Patriots have a net passer rating differential of 13.1, the 10th-highest in the league.

Quarterback Tom Brady is also coming into the playoffs colder than he has since becoming the everyday starter in 2001. Over the last four games of the season, Brady completed 61 percent of his passes, producing a 81.6 passer rating, eclipsing his previous low (86.0 in 2012) by almost five points.

Pittsburgh Steelers (13-3) | AFC No. 2 seed

Pittsburgh has seen its opponents convert on 62 percent of its red-zone opportunities. Only four teams have been worse: the 0-16 Cleveland Browns (67 percent), Green Bay Packers (65 percent), Miami Dolphins (63 percent) and Detroit Lions (62 percent). As you may recognize, none of those teams is in the playoffs.

No Super Bowl winner since 2002 has ended the regular season allowing a red-zone efficiency higher than 60 percent, with the median among the past 15 championship teams checking in at 48 percent. The average among this group is even lower at 46 percent.

Jacksonville Jaguars (10-6) | AFC No. 3 seed

Blake Bortles has been average under center, completing 60 percent of his throws for a 84.7 passer rating. In addition, nine of his 16 starts have produced a passer rating below that, which could be a problem in the playoffs. Over the past 15 postseasons, teams have a 51-111 record (a .315 win rate) when their quarterback fails to achieve a passer rating in excess of 85.

Kansas City Chiefs (10-6) | AFC No. 4 seed

Good luck trying to figure out which Chiefs team is going to show up in the playoffs.

If it’s the team we saw during the first eight weeks, there could be a discussion of the franchise’s first title in the Super Bowl era. Those Chiefs scored 5.5 more points per game than expected based on down, distance and field position, second only to the Patriots (8.2). From Week 9 on, Kansas City managed just 1.3 more points per game than expected.

There is also the problem of their porous run defense. Only the Buffalo Bills allowed more second-level yards per carry than the Chiefs (1.4), perhaps foreshadowing solid rushing performances by the Tennessee Titans, their wild-card opponent (No. 8 in rush DVOA), plus the Patriots (No. 3) and/or Steelers (No. 6), should Kansas City make it past the first round of the playoffs.

Tennessee Titans (9-7) | AFC No. 5 seed

The average passer rating differential for a non-playoff team over the past 15 years has been minus-7.7, with a higher regular season differential indicating the potential for a deeper playoff run. The Titans’ net passer rating differential was minus-10.7. It’s a minor miracle the Titans are even in the playoffs.

Playoff results (2002 to 2016) Average rank of net passer rating differential Average net passer
rating differential
Did not qualify 21st -7.7
Lost wild-card round 11th 7.1
Lost divisional round 8th 13.4
Lost championship game 9th 12.2
Super Bowl appearance 6th 18.9

Buffalo Bills (9-7) | AFC No. 6 seed

Buffalo’s offensive line doesn’t protect its quarterback that well (9.3 percent adjusted sack rate, 31st in 2017), and there has been just one Super Bowl champion in the past five years to rank worse than 22nd in pass protection: the Seattle Seahawks (9.6 percent in 2013, to rank 32nd).

Read more on the NFL:

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