The Sports Xchange

SANTA CLARA, Calif. — Blaine Gabbert might be only 26 years old, but he responded like a veteran when informed Monday that he would replace Colin Kaepernick as the 49ers’ starting quarterback for Sunday’s game against the Atlanta Falcons.

“It’s always kind of a funny deal in the NFL when you hear your number called because you never know when it’s going to be,” he said. “And that’s kind of why you always got to stick to your routine and just always be prepared because, like they always say, you’re one play away from playing and you’re one play away from not playing.”

Gabbert, a second-year 49er, will be making his first start since Oct. 6, 2013, while he was playing for the Jacksonville Jaguars.

He went 5-24 as Jacksonville’s starter, which prompted his benching and, eventually, his contract termination.

“More mature,” he responded when asked what’s different about him now. “When I got in the league as a 21-year-old, you haven’t seen really anything. And going into my fifth year, just the experiences that I’ve had preparing for games, playing in games, being a backup quarterback. It’s valuable over time to have those repetitions in practice and on the game field.”

Gabbert insisted he had no problem with the fact that he hasn’t been given any indication his new gig will last more than just one week.

“I’m just taking it as a chance to go out there and just prove to this team what I can do,” he said. “It’s a great opportunity for me to go out there and play against a good Atlanta football team. I’m just going to go out there and enjoy this. It’s fun to play ball again, especially in the regular season, and we just got to get something going on offense.”

–Three 49ers underwent surgery Tuesday: running back Reggie Bush (knee), safety L.J. McCray (knee) and running back Mike Davis (hand).

Only Bush was ruled out for the season.

Among the players who are uncertain to play Sunday against Atlanta are: running back Carlos Hyde (foot), wide receiver Anquan Boldin (hamstring), cornerback Kenneth Acker (concussion), tight end Garrett Celek (concussion) and punter Bradley Pinion (calf).

The 49ers added a pair of veteran running backs — Shaun Draughn and Pierre Thomas — to replace Bush and Davis. They join Kendall Gaskins, promoted from the practice squad last week, as the only healthy backs leading into the Atlanta game.

NOTES: WR Anquan Boldin has scored five touchdowns in five career games against the Falcons, the 49ers’ opponent Sunday. He has caught 30 passes for 398 yards in those games. … WR Torrey Smith needs 67 receiving yards Sunday against Atlanta to reach 4,000 for his career.