49ers Defense Super Bowl Preview: Will Chiefs Exploit SF on Ground?
After the 49ers put together a three-week stretch of dominant football from Weeks 12-14 — defeating the Seahawks (twice) and demolishing the Eagles — some oddsmakers at prominent sportsbooks had San Francisco power rated 4-5 points better than every other NFL team headed into Week 15.
The 49ers were not only overwhelming favorites to win the NFC, but also the clear and away favorite to win Super Bowl 58. Six weeks later, the 49ers are representing the NFC in Las Vegas, but those same oddsmakers have them just two points better than the reigning Super Bowl champion Chiefs, who were power rated as the third- or fourth-best AFC team as recently as Week 15.
San Francisco boasts an elite offense that broke records for efficiency and dominated supposedly good defenses at various points this season. The primary difference between the power rating of San Francisco then and now is that the market has finally caught up to the clear vulnerabilities present within defensive coordinator Steve Wilks' defense.
Read about why I’m betting the 49ers-Chiefs second-half under in the Super Bowl.
The 49ers have had stretches of good defensive play, but the last month has been anything but. Their run defense has been lackluster all season and the addition of Chase Young hasn’t made a meaningful impact on pressure rate. Watch film of the NFC Championship Game and you’d see Young is a clear net negative in the run game as the Lions targeted him repeatedly.
For all the talk about the Chiefs' porous run defense being a liability, the 49ers have actually been worse against the run this season by EPA per rush and success rate allowed. San Francisco ranks 30th in rush success rate allowed and 27th in rush EPA (postseason included).
The 49ers have been gashed in three of their last four meaningful games this season against the Ravens, Packers and Lions. The last two games were especially concerning — San Francisco allowed Green Bay and Detroit to rush for 5.6 yards per carry and 318 total yards. Only the Seahawks have been worse than the 49ers on a play-to-play basis defending the run since Week 9.
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San Francisco has struggled defending the run in short yardage situations, too, ranking 29th in power success rate allowed. The 49ers play almost exclusively four-down fronts and don’t offer a ton of schematic variation.
You’d expect the data to show that they are worse against teams that go heavy against them, but that hasn’t been the case. San Francisco has struggled the most when teams run on them out of 11 personnel — three receivers, one tight end and one running back. The 49ers were one of the five-worst defenses by success rate allowed when teams ran against them out of 11.
The Chiefs went heavy in last year’s Super Bowl with a ton of 2-3 tight-end sets against the Eagles. The result was 21 total runs with a 48% success rate and 0.15 EPA per play. They picked on a bad run defense and controlled the game and clock in the second half.
Kansas City has the third-highest neutral pass frequency in the NFL this season, but much like last year, the Chiefs’ best path to success might be to increase their run rate.
The quality of the offensive lines and running games are the primary difference between the Chiefs and Packers/Lions. Sure, Kansas City has Patrick Mahomes, but its offense has not been operating at nearly as high of a level as Detroit or Green Bay.
Both NFC foes had elite offensive lines in both run and pass protection. Both the Packers and Lions were top eight in rush success rate entering their respective game against San Francisco — Kansas City is just 21st in rush EPA and 27th in success rate.
The 49ers allowed 52 points in two playoff games, which is the fourth-most points per game allowed by a defense of the 48 that qualified for the Super Bowl this century. San Francisco snuck through two consecutive difficult challenges as a 9.5- and 7.5-point home favorite. The calculus changes now that the vulnerable 49ers defense is facing a worse offense overall and is only a two-point favorite.
As bad as the rush numbers have been, it’s not all bad for the 49ers overall. They did, after all, face two elite offenses in their two postseason games. San Francisco's defense is built on the ability to generate quick pressure, which it was unable to do often enough when facing the excellent offensive lines of Detroit and Green Bay.
The matchup against weaker Kansas City tackles (on paper) seems like an opportunity for San Francisco to rediscover its pass rush. The Lions and Packers were both in the top 10 in pressure rate allowed; Kansas City is 17th. Trying to sack Mahomes is nearly impossible for most defenses, but the 49ers aren’t going to blitz much and may not need to blitz to generate pressure.
There were only three defenses that fared better by DVOA against tight ends than San Francisco. The 49ers run a ton of zone and the Chiefs target Rashee Rice and Travis Kelce when facing zone looks almost exclusively.
The 49ers ranked third in average net yards per attempt allowed in zone defense. They ranked top 10 in QB rating allowed against zones. Thanks to the elite play of linebackers Fred Warner and Dre Greenlaw, the 49ers are the No. 1 defense at covering routes over the middle of the field. They rank fourth in allowing short passes, too.
The best way to attack San Francisco through the air is with vertical passes outside the numbers. The Chiefs don’t really trust their receivers on the outside to win vertically outside the numbers.
San Francisco has won with offense all season long as its defense took a clear step back year over year. This isn't the same ferocious defense under Wilks that it was in years past with Robert Saleh and DeMeco Ryans, and the market is finally reflecting that with the price on this game after weeks of San Francisco inflating spreads.
The 49ers defense can be had — the Ravens and Bengals are examples of healthy AFC offenses having their way — but major questions remain about the explosiveness of Kansas City’s offense entering Super Bowl Sunday.
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