49ers Backup Blaine Gabbert Gets It Done, Stuns Falcons 17-16

© Carlos Avila Gonzalez, The Chronicle Bruce Ellington (10) and Garrett Celek (88) celebrate Celek's second touchdown in the second quarter as the San Francisco 49ers played the Atlanta Falcons at Levi's Stadium…
© Carlos Avila Gonzalez, The Chronicle Bruce Ellington (10) and Garrett Celek (88) celebrate Celek’s second touchdown in the second quarter as the San Francisco 49ers played the Atlanta Falcons at Levi’s Stadium…

Five days after head coach Jim Tomsula said he wanted starting quarterback Colin Kaepernick to “step back and breathe,” Blaine Gabbert stepped up and breathed life into the 49ers’ inert offense, leading a 17-16 win over the Falcons on Sunday.

Given a chance to revive a career that had inspired punch lines, Gabbert was no joke: He completed 15 of 25 passes for 185 yards with two touchdowns and two interceptions in his first start since October 2013. Gabbert also had nine carries for a career-high 32 yards.

The result: The 49ers, who were 2-6 and had scored nine points in their previous two games, stunned a team that was 6-2 and had arrived as seven-point road favorites.

Gabbert threw second-quarter touchdowns of 1 and 11 yards to tight end Garrett Celek to give the 49ers a 17-13 lead and provide hope for a previously listless attack.

The 49ers entered the game ranked last in the NFL in points (13.6) and yards per game (282.3), and they hadn’t scored a touchdown in 130 minutes, 52 seconds, a streak that dated to Oct. 18. In addition, they had scored 10 or fewer points in four of their first eight games for the first time in franchise history.

On Sunday, they scored 10 points in the first 17 minutes and had 17 points at halftime, their largest first-half total since Dec. 20.

However, with the 49ers leading 17-13 midway through the fourth quarter, Gabbert picked an inopportune time to unleash his first awful pass. On 2nd-and-7 at midfield, his 17-yard throw to well-covered tight end Vance McDonald was intercepted by defensive end Vic Beasley Jr.

The Falcons turned the turnover into points. Facing 4th-and-goal at the 2-yard line with 3 minutes left, head coach Dan Quinn chose to kick a field goal and Matt Bryant’s 19-yard kick trimmed Atlanta’s deficit to 17-16.

Quinn gambled his defense would provide another chance at victory, but the Gabbert picked up a first down with a five-yard run on 3rd-and-4 on the 49ers’ next possession. The 49ers picked up another first down to seal their second victory in their past eight games.

Gabbert won over the crowd at Levi’s Stadium. He received an ovation early in the fourth quarter when he returned to the huddle after missing two plays. After taking a huge hit from linebacker Philip Wheeler, who was called for roughing the passer, Gabbert was examined on the sideline for a concussion. Kaepernick threw one pass in his brief cameo, a 20-yard throw that was dropped by tight end Vance McDonald.

Gabbert’s first interception came when a perfectly placed 30-yard strike to Jerome Simpson bounced off the wide receiver’s chest and was corralled by cornerback Phillip Adams in the third quarter.

The quarterback’s performance was even more impressive considering his supporting cast. Wide receiver Anquan Boldin (hamstring) was sidelined, tight end Vernon Davis was traded Monday and the running back corps consisted of Shaun Draughn, Kendall Gaskins and Pierre Thomas, none of whom was on the 53-man roster nine days earlier.

Meanwhile, the 49ers defense, which had also been besieged by injuries, held up against the NFL’s fourth-ranked offense, which had one touchdown and seven punts.

The 49ers were playing without their starting cornerbacks, Tramaine Brock (shin) and Kenneth Acker (concussion), and backup Keith Reaser (ankle) was also sidelined. As a result, Dontae Johnson made his first start of the season and Marcus Cromartie, who was promoted from the practice squad Saturday, made his first career start. Jimmie Ward and Chris Davis, who was signed to the practice squad Tuesday and promoted Saturday, were the other cornerbacks.

The Falcons had 302 yards, and running back Devonta Freeman, the NFL’s leading rusher, managed just 12 yards on 12 carries.

Source: San Francisco Chronicle
Eric Branch is a San Francisco Chronicle staff writer. E-mail: ebranch@sfchronicle.com Twitter: @Eric_Branch