SANTA CLARA -- Once Colin Kaepernick's cameo is over Sunday night, the 49ers might unleash all four of his backups in their exhibition game against the visiting Minnesota Vikings, coach Jim Harbaugh said Friday.
Seneca Wallace joined that cast Thursday after an undisclosed injury limited Scott Tolzien in practice earlier this week, Harbaugh noted.
Tolzien showed no signs of hindrance during Friday's warm-up and was last in the practice rotation behind Kaepernick, Colt McCoy, rookie B.J. Daniels and Wallace. If Tolzien progresses at full speed, he'll play Sunday night.
Wallace's experience and mobility enticed the 49ers, who signed him only three days after he got cut by the New Orleans Saints. He previously played with the Seattle Seahawks and Cleveland Browns but spent last season out of the NFL.
"There's numerous plays in our system that he's done before, whether it was in Cleveland or Seattle," Harbaugh said. "So it's just a matter of learning how we call it, and getting familiar with the quarterback-center exchange.
"Timing with the receivers may not be precise, but to get out and play and compete, I feel he can do that."
Wallace, a Sacramento native, hasn't played in the NFL since his 2010-11 tenure with Cleveland, where he backed up McCoy. Now Wallace is vying with McCoy, Tolzien and Daniels for the No. 2 role behind Kaepernick.
Wallace spent last season happily watching what he called "the transition of the game" to younger, mobile quarterbacks such as Kaepernick, Cam Newton, Russell Wilson and Robert Griffin III.
"When I came in, they didn't glorify that," said Wallace, a 2003 fourth-round draft pick of the Seahawks. "It was, 'We don't want mobile quarterbacks.' Now they're utilizing the kids' talents, and that's a good thing."
Wallace's mobility showed with his 68 career carries for 293 yards and one touchdown, as well as six receptions for 106 yards. Such athletic ability fits in nicely to the NFL's current trend.
"With the advent of a quarterback who can run, extremely athletic and fast, and has the ability to throw the football at an NFL-quarterback level, the NFL hasn't seen that type of player in so much abundance as it does now," Harbaugh said.
"You look at Cam Newton, Colin Kaepernick, Robert Griffin, Russell Wilson and there's others that fit that mold, Ryan Tannehill. They're big, fast and throw the ball very effectively.
"There's a new wave of quarterbacks. I don't think that's any revelation. But teams are studying how to defend these players, and they're finding out that's a pretty good combination to be athletic and throw the ball as well as these guys do."
Lattimore continues to rehabilitate well from an October hit that tore three ligaments in his right knee. "Things have been going good. Patience, that's all it is now," said the fourth-round draft pick, who'll remain on the NFI list through at least mid-October.