The X-factors that could determine the NFL conference title games

What’s an “X-factor” for an NFL team? It might be an under-noticed duo with game-changing abilities, capable of creating unpredictable and crucial plays. It could also be clutch performers in high-pressure situations, or momentum shifters.

Essentially, the “X-factor” tries to capture an unusually impactful element of a team that could swing a game’s final result, even if would never appear on a network highlight reel or Super Bowl promo.

Often, these players or position groups don’t get the attention of their peers or teammates. We’re going to change that. Using traditional and nontraditional metrics, we scoured the rosters and statistics of the four remaining playoff teams and picked a high-performing unit from each to get on your radar before its members become household names – or even if they never do.

Baltimore Ravens

Linebackers who excel in pass coverage

Baltimore defensive coordinator Mike Macdonald – a popular head coaching prospect this month – has a lot of special players on his unit, but the ones to watch might be his linebackers, a versatile group with strong coverage skills who can disrupt the opponent’s passing game, limit big plays and contribute to game-changing defensive stops. If we weight each linebacker’s Pro Football Focus pass-coverage grade for the number of snaps played in coverage, Baltimore’s linebackers have the second-highest weighted grade this season, including the playoffs. Only the New York Jets were better as a group.

The star here is Roquan Smith, who is credited with 165 total tackles (fifth most among all defenders) and seven tackles for a loss this season, including the playoffs. He is the sixth-highest rated linebacker in pass coverage, according to Pro Football Focus, with only San Francisco’s Fred Warner ahead of him among linebackers whose teams are still alive, yet don’t call him one-dimensional. He has 25 stops at or behind the line of scrimmage against opposing rushers, too. Then there’s Patrick Queen, a first-round pick in 2020 credited with four pass breakups and an interception this season.

Those two could be key in defending Kansas City’s tight end Travis Kelce, who is usually effective against opposing linebackers. Last week, Kelce caught both targets when matched with Buffalo middle linebacker A.J. Klein, gaining 44 yards and two first downs. In the Chiefs’ first-round win over the Miami Dolphins, Kelce caught all three targets when he was matched with Miami’s linebackers, racking up 46 yards and three first downs. Yet against New England’s Mack Wilson Sr., PFF’s fourth-highest rated linebacker in coverage this season, Kelce had one catch for 4 yards. If Baltimore’s linebackers can stifle Kelce, the Ravens could be in terrific position to advance.

Kansas City Chiefs

Elite pass protection from the offensive line

Kansas City’s defense has improved significantly this season and has been given credit for much of the team’s success, especially with Patrick Mahomes and the offense having unusual struggles. Don’t overlook how well the Chiefs’ offensive line is performing. Donovan Smith, Joe Thuney, Creed Humphrey, Trey Smith and Jawaan Taylor, when lined up together, have allowed 15 sacks over 462 Mahomes drop-backs, leading to a sack rate far below average (3.2% compared to a league average of 7.1%). It’s not all Mahomes’ athleticism keeping this rate low; Pro Football Focus divides the responsibility for a sack between quarterback and blockers, and rates the Chiefs’ pass protection as the sixth best in the NFL this season, including the playoffs.

Obviously, the more clean pockets Mahomes has, the better he will perform. His completion rate is 75% when not facing pass pressure, earning a passer rating of 108.0 (sixth among qualified quarterbacks). Those numbers decline to 49% and 60.7, respectively, when facing pass pressure, per data from Pro Football Focus. Of concern: Thuney, a first-team all-pro, was injured in the divisional round and could be unavailable against the Ravens.

Detroit Lions

An unusually efficient running game

Coach Dan Campbell and offensive coordinator Ben Johnson – another top candidate in this hiring cycle – aren’t overly obsessed with running the football, but when they do run it, the Lions are one of the most efficient teams at gaining yards and improving field position. According to analyst Aaron Schatz, the Lions lead the league in adjusted line yards, a formula that takes all running back carries and assigns responsibility to the offensive line based on how many yards were gained, adjusted for down, distance, situation, opponent and the difference in rushing average between formations. For context, last year’s champion, the Kansas City Chiefs, had the third-highest adjusted line yards. In 2021, the champion Los Angeles Rams ranked sixth, while the 2020 champion Tampa Bay Buccaneers ranked ninth.

Veteran David Montgomery and rookie Jahmyr Gibbs have a combined 2,149 rushing yards and 26 rushing touchdowns during the regular season and playoffs. Gibbs is also averaging 5.3 yards per carry when facing seven or more defenders in the box, meaning the opposition is geared toward stopping the run. The league average is 2.1 yards per carry in these situations, per data from TruMedia. You have to give credit to Detroit’s offensive line, too, especially right tackle Penei Sewell, who is ranked No. 1 overall among all offensive linemen for run blocking this season, according to Pro Football Focus.

San Francisco 49ers

Disruptive pass pressure from interior defensive linemen

All eyes, and double teams, are on four-time Pro Bowl edge rusher Nick Bosa. That allows less-heralded defensive linemen Javon Hargrave and Arik Armstead to create successful pass pressure of their own.

Hargrave, an offseason free-agent acquisition who helped the Philadelphia Eagles reach last year’s Super Bowl, was this season’s fourth-best pass rusher among interior defensive linemen, per Pro Football Focus. He has 44 tackles (eight for loss), seven sacks and 14 quarterback hits. Armstead, a nine-year veteran who has spent his whole career in San Francisco, has dealt with plantar fasciitis in his right foot, but that hasn’t stopped him from producing 30 tackles, five sacks and 13 quarterback hits over 13 games during the regular season and playoffs. He is rated as the sixth-best pass rusher among interior defensive linemen, per Pro Football Focus.

Through their sacks, hits and hurries, Hargrave and Armstead are estimated to have prevented opponents from scoring 40 total points this season, per NFL play-by-play data. The 49ers had the league’s third-highest rated pass rush this season, per Pro Football Focus, and they accomplished that without relying on the blitz – they had the league’s eighth-lowest blitz percentage. Hargrave and Armstead are a big part of the explanation.