The Braves placed Jordan Walden on the disabled list Saturday with a strained left hamstring, a blow for the Braves bullpen which has counted on him as one of their top setup men.

The Braves recalled left-hander Ian Thomas from Triple-A Gwinnett to take his place. Walden’s injury is another reason the Braves moved Alex Wood to the bullpen, at least for a few more days. (Wood is scheduled to start against on Saturday in St. Louis.)

Walden said his hamstring has been bothering him off and on since spring training. But he felt it tighten up on his second to last pitch to Angel Pagan as he finished out the eighth inning of his last appearance against the Giants on May 4, last Sunday.

“That one kind of just told me ‘All right, that’s enough,’” Walden said. “I need to make sure that gets better before I hurt my arm or hurt something else.”

Walden had given up a walk and a two-run home run to Brandon Belt earlier in that inning, snapping a streak of 10 straight scoreless appearances out of the Braves bullpen. Walden had not pitched in the four games since.

He said he tried to throw a bullpen a day or so ago and couldn’t get through it.

The DL move is retroactive to May 5 and the Braves will hold out hope he can return after 15 days, but it’s hard to predict yet. When the Braves leave for San Francisco on Sunday, Walden will head for Orlando, where he’ll continue to receive treatment at the Braves’ complex there. He hopes to play catch by the middle of the week.

“Every day I get better so hopefully just these 15 days and that’ll be it,” Walden said. “But the hammy will tell me when it’s ready.”

Walden missed significant time coming down the stretch last season with injuries to both groin muscles. He appeared in only four games of the Braves’ final 36 last season. He is susceptible to leg problems given his unorthodox delivery.

“It’s a violent delivery leg-wise,” Braves manager Fredi Gonzalez said. “Catapults out of there and it’s tough on his left leg.”