49ers vs. Dolphins score, takeaways: San Francisco beats Miami but loses Jimmy Garoppolo for season

The 49ers might have to rely on their potent defense the rest of the way

Mike McDaniel learned under Kyle Shanahan, and he returned to San Francisco on Sunday with the intention of beating his mentor, and tying the Bills atop the AFC East in the process. It was not meant to be. The Dolphins coach may have forecast a big win when San Francisco lost starting quarterback Jimmy Garoppolo to a foot injury early in the Week 13 matchup -- an injury we learned following the game that will sideline Garoppolo for the rest of the season. But his own starter, Tua Tagovailoa, struggled for much of the first half against the 49ers' persistent defense. A late comeback effort kept things close, but rookie Brock Purdy ultimately outdueled Tagovailoa as San Francisco rolled past Miami, 33-17.

Tagovailoa connected with Tyreek Hill for some gaudy numbers, as per usual, but had one of his sloppiest overall performances of an otherwise promising 2022 campaign. With Nick Bosa starring for DeMeco Ryans' "D" off the edge, the QB finished with three turnovers, throwing a pair of picks, fumbling once and nearly tossing additional interceptions in tight coverage. Purdy, meanwhile, wasn't perfect filling in for Garoppolo, but leaned on Christian McCaffrey and Deebo Samuel to secure the win.

The 49ers improve to 8-4 and remain atop the NFC West with the victory, while dropping the Dolphins to 8-4.

Here are additional takeaways from Sunday's contest:

Why the 49ers won

Kyle Shanahan came to coach. Up against his former second-hand man, he drew up a perfect on-the-fly game plan for Brock Purdy, the rookie thrust into an unofficial start after Jimmy Garoppolo left with what we now know is a season-ending broken foot. Basically it just involved feeding the typical ball-carriers, Christian McCaffrey and Deebo Samuel. But it worked; neither play-maker had a gaudy stat line, but they stepped up on several key third downs to help San Francisco dominate time of possession. Like the Jimmy G of old, Purdy played his part by mostly staying in the background. Even better: DeMeco Ryans' defense, which got a monster outing from Nick Bosa (three sacks) to bring Tua Tagovailoa back to Earth, and had sticky hands in the secondary with three picks.

Why the Dolphins lost

Mike McDaniel's offense finally met a legitimate defense. Tua Tagovailoa showed resilience, giving Tyreek Hill another dose of big numbers thanks to frequent shots. But the QB was thrown off early, misfiring on mistimed routes and failing to protect the ball in a game that could've easily tipped in Miami's favor due to the Garoppolo exit. It didn't help that he had zero ground support, but his own ill-advised darts were the primary reason for the Dolphins' defeat. Defensively, the team just could not get off the field on key downs, even knowing Purdy's limitations. And despite logging four sacks and 10 QB hits, as well as a pick, it never felt as if it held an upper hand on San Francisco's emergency signal-caller.

Turning point

Trailing by seven since late in the second quarter, when the 49ers reeled off an 11-play scoring drive in which Purdy hit McCaffrey for a TD, the Dolphins advanced into enemy territory early in the third with a deep shot to Tyreek Hill, which got better thanks to a roughing-the-passer call on Bosa. But then San Francisco finally took advantage of Tagovailoa slinging it into traffic with the following turnover ...

Play of the game

Tagovailoa got a way with a handful of potential picks out of the gate, but Jimmie Ward made him pay by laying out and over former teammate Jeff Wilson Jr. for the first takeaway of the day. The acrobatic interception turned the tide and set the tone for an afternoon eventually littered with Dolphins turnovers:

What's next

The 49ers (8-4) will stay at home in Week 14, when they're set to host the Buccaneers (5-6), who take on the Saints this Monday. The Niners lead the NFC West but are down to their third-string QB in Purdy the rest of the way. The Dolphins (8-4), meanwhile, will hit the road for a "Sunday Night Football" matchup with the Chargers (6-6), who fell to the rival Raiders on Sunday.

[Dec 4, 2022 at 6:51 pm ET · Cody Benjamin]

Tua and Tyreek showing a lot of grit on these key downs in the fourth quarter. Clock is ticking below 10 minutes now, and Miami refuses to bow out. 49ers hold the lead, but barely, as the Dolphins dink and dunk their way closer to scoring range.

[Dec 4, 2022 at 6:36 pm ET · Cody Benjamin]

Tua did not give up on this game, apparently. Just uncorked a perfect deep shot to Tyreek, floating it into open space and letting the speedster track it for the big TD. We've got ourselves a ballgame once more.