For the second straight week, 49ers backup quarterback C.J. Beathard replaced the starter.
This time, Beathard relieved Jimmy Garoppolo after the 49ers trailed the Miami Dolphins 30-7 at halftime Sunday at Levi's Stadium. Garoppolo, making his first start since sustaining a high ankle sprain in Week 2, was pulled in order to avoid further injury risk.
"That is because I want to protect Jimmy," 49ers coach Kyle Shanahan told Fox Sports sideline reporter Lindsay Czarniak.
Garoppolo completed just seven of his 17 pass attempts for 77 yards in the first half, throwing two interceptions and no touchdowns. He ended his day with a 15.7 passer rating, which the Associated Press' Josh Dubow found was the fourth-lowest by a 49ers starting QB since 1979.
Garoppolo played perhaps his best half of the season in Week 2 against the New York Jets, completing 14 of 16 passes for 131 yards and two TDs. Nick Mullens played in place of Garoppolo in the second half after he sustained a high ankle sprain, and Sunday was Garoppolo's first appearance since then.
The 49ers went 1-1 in Mullens' two starts. He was dominant against the New York Giants in a Week 3 win, but Beathard replaced Mullens last week during the fourth quarter of the 49ers' 25-20 loss to the Philadelphia Eagles. Mullens had been ahead of Beathard on the 49ers' depth chart since replacing him in the 2018 season after Garoppolo sustained a torn ACL, but Shanahan told reporters last week that Beathard had supplanted Mullens on the depth chart.
Mullens was inactive Sunday.