How the 49ers lost their touch in the fourth quarter of upset bid against Detroit

It was a night of no punts from either team and unrelenting offensive fireworks from both of them. It ended in even more disappointment for the 49ers, whose dreary season stumbles toward a merciful close.

But while they lost, 40-34, to the NFC-leading Detroit Lions, the 49ers did show a good chunk of the punch that they believe can thrust them back into contention come 2025.

It was on display from the very start.

First, Jauan Jennings visibly annoyed Detroit defensive back Brian Branch, whom he pushed backwards 30 yards downfield on an early running play. Shortly thereafter, the 49ers wideout incensed Terrion Arnold, pile-driving the Lions cornerback through the end zone so thoroughly that his Detroit teammate, Kerby Joseph, parachuted in to instigate a post-play shoving match.

Offsetting flags flew, and it was immediately clear that this rematch of January’s NFC Championship Game — although it carried no postseason implications for either team — would be the spirited affair that the 49ers had vowed they would deliver.

“I thought the guys played real hard,” 49ers coach Kyle Shanahan said. “I thought they competed. I thought they had every chance to beat a real good football team there.”

The 49ers bullied the Lions’ injury-riddled defense, ultimately racking up 475 yards of total offense on a gaudy 7.9 yards per play. But San Francisco’s own beleaguered defense performed even worse than Detroit’s, failing to register a takeaway for the third straight game. And on a night featuring three more misses from 49ers kicker Jake Moody — two via field goal and one on an extra point — the 49ers dropped to 6-10 and secured a last-place finish in the NFC West.

Quarterback Brock Purdy opened the game with perhaps the best half of his career. He threw for 200 yards on a perfect passer rating in the first half, overcoming the depletion of the 49ers’ offensive line in front of him. It was operating with its fourth-string left tackle and backup left guard.

But Shanahan abandoned offensive balance down the stretch, calling 16 straight pass plays in the fourth quarter for Purdy, who injured his right elbow and exited the game after tacking a sack on the final one of those plays. Early tests indicated Purdy’s UCL, which he tore in the NFC title game to close the 2022 season, is intact, but he’ll undergo further testing on Tuesday.

Purdy’s 10th consecutive throw of that pass-happy stretch turned into Joseph’s second interception of the night and helped finally put the Lions in firm control. Shanahan said Joseph read Purdy’s eyes and “teed off” on the attempt to rookie receiver Ricky Pearsall. Such aggressiveness became much more feasible for Detroit after the 49ers deserted their rushing counter-threat.

Afterward, Purdy said the pass-happy trend was a product of success the 49ers had seen through the air up until that point. He finished with 377 yards on 35 attempts, two passing touchdowns and a rushing score.

“Going into the game, we didn’t say anything like that, like ‘Hey we’re going to throw, throw, throw,'” Purdy said. “Obviously, we go into the game with the mindset of we need to run the ball first and that opens up everything else. But just the flow of the game, how it was going, I think our guys winning in man coverage, all that kind of stuff helped and we were in a groove.”

The 49ers were indeed cooking against man coverage, which marked a very positive development for a team that had entered this game ranking dead last in average separation at the time of completion, per NFL Next Gen Stats. Pearsall exploded for a career-high 141 yards. Tight end George Kittle eclipsed the 1,000-yard mark for fourth time in his career, racking up 112 yards. Jennings and running back Isaac Guerendo amassed 67 and 65 receiving yards, respectively.

But the 49ers only handed the ball off 14 times, and that fell woefully short of Detroit’s 30 carries for 149 yards. That was a heavy dose of rushing success that ensured the Lions would control the game’s flow and keep quarterback Jared Goff, who threw for 303 yards of his own, on schedule.

One reason that Joseph, whose two picks ran his NFL-leading mark to nine interceptions, could prey so aggressively on Purdy’s passes was based in that difference. The 49ers simply strayed away from the balance that had kept Detroit’s defense on its heels.

On the other side, the 49ers looked generally helpless. Their run defense, which entered ranked No. 24 in DVOA (defense-adjusted value over average), looked vastly inferior to a Lions rushing attack ranked No. 2 in the league. Their pass defense, though it did register a big fourth-down end-zone stop courtesy rookie DBs Renardo Green and Malik Mustapha, rarely enjoyed down-and-distance leverage and was burned by a touchdown on a hook-and-lateral trick play even when it did.

Detroit racked up a long list of big plays all while the 49ers didn’t come close to countering the onslaught by forcing a single turnover.

“We led the league last year in takeaways,” 49ers safety Ji’Ayir Brown said in the locker room. “I don’t know what is going on this year. It is just sad.”

Then, of course, there was the case of Moody, the second-year man who’s now missed nine kicks since returning from a high ankle sprain in November. The 49ers lost by six points in a game where Moody’s missed kicks left seven points on the table.

“Definitely one of the lowest times of my career, dating back to when I first started football,” Moody said in the locker room. “So confidence, you just have to keep it high. You have no other choice as a kicker. You just have to keep staying confident in yourself. Otherwise, you have nothing.”

With just the season finale at Arizona remaining before the offseason, the 49ers — losers of three straight games ever since it appeared they might be changing course with a resounding victory over the Chicago Bears — are in a situation that might bear at least some resemblance to Moody’s. They’re striving to maintain confidence through disappointment.

Their prolific offensive production through most of Monday’s loss can be used as a building block for that all. Meanwhile, their profuse struggles elsewhere might be discouraging. But Shanahan insists on considering the totality of his team’s performance as this critical offseason nears.

“I think everything is connected,” Shanahan said. “Good or bad, I think it can lead to good things the next year. We’re going through this. By no means are we happy with what we’re going through, but I fully expect us to get better for going through this.

“I expect us to learn a lot here going through this stuff and I expect it to make us a better team next year. And when the season is over, I can’t wait to get started figuring out how to do that.”