Buffalo Bills head coach Sean McDermott talks with an official during the second half Sunday in Orchard Park. AP Photo

ORCHARD PARK — Josh Allen’s extraordinary fourth-quarter comeback against the Ravens didn’t entirely overshadow a major concern for the Bills on the other side of the ball.

Buffalo’s defense barely served as a speed bump against Lamar Jackson and Derrick Henry through the first 48-plus minutes of its season opener on Sunday night. Giving up 40 points and allowing Baltimore to score on seven of its first eight possessions is no recipe for success.

But first, the good news, a day after Buffalo overcame a 15-point deficit in the final four minutes for a stunning 41-40 win capped by Matt Prater’s 32-yard field goal as time expired.

Allen wouldn’t have been in position to engineer the 22nd game-winning drive of his eight-year career if not for the defense finally making a contribution.

Tackle Ed Oliver opened the door for the comeback by punching the ball out of Henry’s arms with 3:06 remaining. And Allen wouldn’t have gotten the ball back with 1:26 left if not for the defense forcing a three-and-out. Cornerback Christian Benford limited DeAndre Hopkins to a 7-yard catch on third-and-9.

“He played unbelievable,” Allen said of Oliver, who also had a sack and tackled Henry for a loss. “It takes everybody doing their job and it takes a few guys doing more than their own job, and I think Ed did that.”

Those few plays aside, Allen, last season’s MVP, had to be especially MVP-like for Buffalo to win. He threw for 251 yards in the fourth quarter alone — the most in the final 15 minutes since Boomer Esiason had 252 for Arizona in a win over Washington in 1996.

Entering the season, the defense was considered the team’s weakest link. And the unit has come up short in the playoffs over the past five years. Buffalo has allowed averages of 33.2 points and 426 yards of offense — including 150 yards rushing — in each of its last five playoff losses. Four of those were to Kansas City.

If there is a bright side, Sunday’s win came in Week 1 and against a potent Ravens offense that last year became the first to top 4,000 yards passing and 3,000 yards rushing. There are few opponents in the upcoming weeks, starting with the New York Jets, that can boast that type of production.

Another hopeful sign is that reinforcements are on the way.

The Bills opened without two veteran free-agent additions in edge rusher Michael Hoecht and tackle Larry Ogunjobi, who are serving six-game suspensions for violating the NFL’s policy on performance enhancers. Buffalo was also down starting cornerback Tre’Davious White, sidelined by a groin injury.

The defense is also young, with coach Sean McDermott putting faith in the unit gradually developing. Buffalo used six of nine draft picks on defensive players, including the first five.

How long that will take remains to be seen, though McDermott noted it’s easier making corrections entering Week 2 following a win.

“It wasn’t even close to what I would expect us to be able to get to,” McDermott said. “We can be better. But I really do appreciate how they stuck together. And that’s true of this whole team.”

WHAT’S WORKING

Allen and the offense continued last season’s share-the-wealth approach. Five players caught at least four passes, including running back James Cook, who had five catches for 58 yards and added 13 carries for 44 yards and a touchdown.

WHAT NEEDS HELP

Stopping the run. Jackson averaged 11.7 yards per carry and Henry 9.4, including TD runs of 30 and 46 yards. The 238 yards rushing allowed were the most by Buffalo since giving up 271 in a 35-10 loss at Baltimore in Week 4 last season.

STOCK UP

Keon Coleman. Despite a few drops, including a 2-point conversion bouncing off his hands, the second-year receiver had eight catches for a team-best 112 yards, including a touchdown catch on a pass tipped at the goal line.

STOCK DOWN

Safeties Taylor Rapp and Cole Bishop were too often out of position or getting stiff-armed out of the way when they tried to stop Henry.

INJURIES

Returner Brandon Codrington had his knee examined and re-entered the game.

KEY NUMBER

12-0 — Buffalo’s regular-season home record since a 24-22 loss to Denver on Nov. 13, 2023.

NEXT STEPS

Travel to face the Jets to open a stretch of facing three AFC East rivals over four weeks.