SANTA CLARA — There will be no shakeup in the quarterback order in the 49ers’ third and most important preseason game, Jim Harbaugh said Friday. Blaine Gabbert will be the second passer off the bench, followed by Josh Johnson and McLeod Bethel-Thompson.

“Blaine is that guy right now,” Harbaugh said of the No. 2 quarterback.

Gabbert has struggled in the teams’ first two exhibition games, and Harbaugh said after Sunday’s loss to Denver that whoever doesn’t turn the ball over will win the job.

Gabbert has completed 11 of 25 passes for 60 yards with two interceptions and a 17.9 rating. Johnson also has two turnovers — both of them fumbles — while Bethel-Thompson also has thrown two interceptions. Harbaugh said he would not look outside the team for a backup. No 49ers quarterback has engineered a touchdown drive. Bethel-Thompson is the only quarterback on the roster with practice-squad eligibility.

“I don’t judge it off just those,” Harbaugh said of the bleak statistics his quarterbacks have accumulated. “I’ve been pretty clear what I thought we needed to get better as, as a unit. Team-oriented offense that has precision and plays wells together, all 11, and that’s what we’re going to be striving for.

“And we’ve had a good week,” he said. “Feel like we made progress.”

Harbaugh said that Glenn Dorsey’s bicep surgery went well and that the hope is Dorsey could return in 3½ months. That would make him a good candidate for injured reserve with a designation to return, which would means that Dorsey would not occupy a roster spot until he’s ready to come back in the second half of the season.

“There’s a very good chance of that,” Harbaugh said. “(There are) still things that can happen before that decision could be made.”

The 49ers must decide which player — teams only can pick one — gets that designation by Sept. 2.