Brock Purdy's Biggest Mistake in the 49ers' Loss to the Jaguars

Brock Purdy reflects on his Week 4 performance.

Sep 28, 2025; Santa Clara, California, USA; San Francisco 49ers quarterback Brock Purdy (13) passes the ball during the first half against the Jacksonville Jaguars at Levi's Stadium. Mandatory Credit: Kyle Terada-Imagn Images | Kyle Terada-Imagn Images

San Francisco 49ers starting quarterback Brock Purdy returned after suffering shoulder and turf toe injuries in Week 1.

In their first loss of the season, a 26-21 defeat to the Jacksonville Jaguars, his return highlighted areas that still need vast improvement.

Post-game, he made it known that what he produced out on the field wasn't up to his or the organization's standards.

Purdy's fumble cost the game

San Francisco 49ers quarterback Brock Purdy (13). | Darren Yamashita-Imagn Images

Although the 49ers struggled all game, their hopes of maintaining a perfect record were dashed when former Niner Arik Armstead forced a fumble on Purdy, just as the secondary had set up a potential game-clinching drive.

The play inevitably allowed the Jaguars to start running down the clock with 2:44 remaining in the fourth quarter.

Purdy was seen pounding the grass after the play, a very rare sight since he became the starting quarterback. In his post-game interview, he shared the intense emotions he was feeling in that moment with reporters.

"Yeah, just the whole thing. For us to turn the ball like that throughout the game and then have a chance to win the game at the end. Our defense just played their butt off and gave us a chance," he said.

"Then we get the ball rolling and then we had an opportunity to possibly take a shot and go deep and then obviously the ball goes on the ground. I was mad over everything, the opportunity we had right there to get back in the game, what we had done all day, for myself, with the ball. So, I was just frustrated in the moment for sure.

Purdy's turnovers and interceptions were crictial errors

San Francisco 49ers quarterback Brock Purdy (13). | Kyle Terada-Imagn Images

On top of the late fumble, Purdy turned the ball over four times and threw two interceptions during the game. It’s a clear sign that he’s lacking sharpness, having only played two games this season.

The reality is this is likely a one-off game for Purdy, but it doesn't take away the fact that certain decision-making cost the 49ers big time on certain drives.

"We can't do it [turnovers], it's the NFL," Purdy admitted.

"It starts with me throwing better balls and being smart with the ball. So, I think it really starts there. I just got to be better.

"But outside of that, as an offense, it's something that we harp on every single day and our team knows it."

Purdy has the chance to quickly move past this performance in Thursday’s match against the Los Angeles Rams. The 49ers face their toughest test yet, but they also have the opportunity to start 3-0 in the NFC West.