Denver Broncos vs San Francisco 49ers Prediction

San Francisco should beat Denver at Levi's Stadium on Sunday by about three points. Brock Purdy has been the most efficient passer in football through three weeks, and Denver's run defense has struggled, but the 49ers will be without three defensive linemen, which gives Bo Nix and the Broncos a real chance to keep it close. The market has San Francisco favored by 3, the same as our number, so there is no official play on this game. This is our forecast only.

How both teams got here

San Francisco is 3-0. The 49ers opened the season by beating the Rams 27-7 in Melbourne, handled Miami 35-13 at Levi's Stadium in Week 2 and held off Arizona 36-30 at home in Week 3, when Brock Purdy threw four touchdown passes and found George Kittle for the clinching score with 1:31 left. Denver is 2-1. The Broncos lost 31-10 at Kansas City in Week 1, beat Jacksonville 20-13 at home in Week 2 and then rallied from 16-0 down at halftime to beat the Rams 30-26 on Sunday night in Week 3. Bo Nix scored the winner on a one-yard run with 47 seconds left, and safety Talanoa Hufanga returned an interception 66 yards for a touchdown and picked off Matthew Stafford again on the final play.

San Francisco's case

The 49ers' offense has been as efficient as any in the league. Purdy leads the NFL with a 133.1 passer rating, has nine touchdown passes, is completing 72.3 percent of his throws and has not been sacked through three games. Measured by expected points added per dropback, a stat that tracks how much each pass play helps the offense, he ranks first in the league in our tables built from nflverse play-by-play data. San Francisco averages 32.7 points per game, leads the league in third-down conversions and has scored touchdowns on nine of its ten red zone trips, according to the Broncos' own game preview.

Kittle has 174 receiving yards and three touchdowns, Christian McCaffrey has 270 scrimmage yards and three touchdowns, and Deebo Samuel turned a hook-and-ladder into a long gain against Arizona. The protection in front of Purdy grades as the best in the league in our numbers. There is also a matchup in San Francisco's favor on the ground. Denver's run defense, one of the best in football last season, ranks last in the league this year in expected points allowed per rush, which gives Kyle Shanahan's run game a chance to set the tempo with McCaffrey practicing fully.

The caveat is the schedule. The 49ers have beaten a Rams team playing overseas, a Miami team starting Malik Willis and an Arizona team starting Jacoby Brissett. Denver's defense is the best unit San Francisco will have faced.

Denver's case

The Broncos' strength is on defense. Denver ranks fourth in the league in pressure rate, has eight sacks through three games and plays sound coverage behind it, with Pat Surtain II and Riley Moss at cornerback and Hufanga coming off a game in which he became just the fifth safety in league history with two interceptions, a sack and a pick-six. Against the Rams the defense hit Stafford 14 times. Head coach Sean Payton also has a line that protects Nix well; Denver allows a sack or quarterback hit on about one of every six dropbacks, among the best rates in the league.

The offense has been uneven. Nix was efficient against Jacksonville but struggled at Kansas City, where the Broncos faced steady pressure, turned it over twice and went three and out four times. Against the Rams they also had four three-and-outs before the second-half comeback. The running game has started slowly every week. Denver averages 81.0 rushing yards per game and had 23, 32 and 21 rushing yards in the first halves of its three games. "We haven't run it consistently well enough, clearly," Payton said this week. J.K. Dobbins leads the team in rushing, and Jaylen Waddle, Courtland Sutton, a returning Marvin Mims and Evan Engram give Nix a full set of targets.

Injuries and lineup news

This is where the game gets interesting. San Francisco's defensive front is badly depleted. The 49ers ruled out defensive end Nick Bosa (knee, calf), defensive end Mykel Williams (knee) and defensive tackle James Thompson Jr. (ankle), and defensive tackle C.J. West is on injured reserve. Defensive end Keion White (hamstring) and linebacker Dre Greenlaw (quadriceps) are questionable after missing two practices and returning to the field late in the week, and linebacker Jaden Dugger (shoulder) is also questionable. Defensive end Romello Height (hand) and left tackle Trent Williams (neck) were cleared to play.

The 49ers' receiver room is thin as well. Receivers Kirk, Robinson and De'Zhaun Stribling are all on injured reserve, and Mike Evans (ribs) is questionable. Shanahan called Evans a game-time decision. That leaves more of the passing load on Kittle, Samuel and McCaffrey.

Denver is close to full strength. Outside linebacker Dondrea Tillman (hamstring), a rotation pass rusher, is the only Bronco ruled out. Waddle, Mims, Dobbins and defensive linemen Zach Allen and D.J. Jones were all full participants on the final report. Both starting quarterbacks are healthy. Inactive lists will settle the status of Evans, White and Greenlaw shortly before kickoff, and if both White and Greenlaw sit, Denver's offense gets an even softer front to work against.

How the matchup sets up

Our interpretation is that three things decide this game. The first is strength against strength: San Francisco's passing game against Denver's pass rush and secondary. The Broncos bring the best rush Purdy has seen this season, but the 49ers' protection and Purdy's quick processing have held up against everyone so far, and Tillman's absence trims Denver's rotation on the edge. "He's through his progressions fast," Payton said of Purdy.

The second is the reverse matchup. With Bosa, Mykel Williams and Thompson out, Nix should see his cleanest pockets of the season behind a line that already protects him well. That is the main reason we do not have San Francisco winning by more. Without Bosa against Arizona, the 49ers' defense was on the field for 80 plays and allowed 30 points.

The third is the ground game. Denver's run defense has struggled all season, and Shanahan's offense is built to punish that, which could let San Francisco control the clock and keep Nix on the sideline. Turnover luck has helped both teams so far, with Denver's pick-six against the Rams and San Francisco's clean ball security, so we treat that as roughly even. Kickoff is expected to be warm and dry at Levi's Stadium, and both teams come in on normal rest.

The key risk

The biggest threat to this forecast is Denver's defense doing to San Francisco what it did to the Rams in the second half. The Broncos rank among the league's best at pressuring the quarterback and taking the ball away. If Surtain and Moss smother a receiver group already missing several players, the pass rush finally gets home on Purdy and Denver wins the turnover battle again, San Francisco's thinned front may not be able to get the Broncos' offense off the field. Purdy's pace of efficiency is also hard to sustain for long, and a game against his toughest opponent yet is a natural place for it to cool off.

Who's in and who's out

Availability as of October 4 at 3:28 PM ET. Each player's role is checked against the snaps he actually played, not just the depth chart, so a starter and a backup on the same injury report are not treated alike. This updates automatically as the injury report changes.

Denver Broncos

Dondrea Tillman, linebacker, out: a rotation player. Snap share over the last three games: 46 percent, 31 percent, 31 percent. Next up on the depth chart: Jonathon Cooper, who has not played a snap this season.

Jonah Coleman, running back, injured reserve: a rotation player. Snap share over the last three games: 6 percent, 40 percent, did not play.

Also listed, all reserves who rarely play: Tyler Onyedim, Kage Casey, Sam Ehlinger, Dallen Bentley.

San Francisco 49ers

Nick Bosa, defensive end, out: a verified starter. Snap share over the last three games: 59 percent, 68 percent, did not play. Next up on the depth chart: Ogbo Okoronkwo, who has been playing a regular rotation share.

Trent Williams, offensive tackle, on the practice report (neck): a verified starter. Snap share over the last three games: 100 percent, 85 percent, 59 percent. Next up on the depth chart: Vederian Lowe, who has been playing a regular rotation share.

James Thompson Jr., defensive tackle, out: a rotation player. Snap share over the last three games: 34 percent, 36 percent, did not play. Next up on the depth chart: Alfred Collins, who has not played a snap this season.

Romello Height, defensive end, on the practice report (hand): a rotation player. Snap share over the last three games: 49 percent, 54 percent, did not play. Next up on the depth chart: Khalid Kareem, who has already been playing a starter's share.

Also listed, all reserves who rarely play: Ephesians Prysock, Kurtis Rourke, Jordan James, Enrique Cruz Jr., Tatum Bethune, Christian Kirk and others.

The verdict

We expect San Francisco to win by about three points, with Purdy's efficiency and the 49ers' run game outweighing an injury-thinned defensive front. The market has San Francisco favored by 3, the same as our number, so there is no official play on this game.