Last year, when the A’s looked to improve before the trade deadline, they did something a little surprising: They beefed up an already superb bullpen.

They’re likely to do the same thing in the coming month, and this time, the relief staff is in need of reinforcement after rough stretches in the first half. Closer Blake Treinen, an All-Star last season, is on the injured list with a mild shoulder strain and Lou Trivino has been temporarily reassigned from his setup role until he gets back on track.

“I think the bullpen is probably the first place we look, not because we don’t like the group we have here but because it’s been less consistent than it was last year — which was inevitable,” general manager David Forst said on The Chronicle’s A’s Plus podcast Monday. “We were never going to perform as well as we did in the bullpen last year. Some of the numbers that were thrown out were ridiculous, and they’re not going to happen again the next year, but I do believe adding one or two people to that unit could help it going forward.”

The A’s could find bullpen support from returning starters A.J. Puk and Jharel Cotton, who are on limited pitch counts, Forst said, but adding help from the outside often can have a quick impact on a club because relievers can work more frequently than starters. Of course, Oakland lost starter Frankie Montas to an 80-game suspension Thursday, and the A’s did pick up Mike Fiers after the trade deadline last year, but, Forst said, “You add a starter toward the end of July, there’s a limited number of appearances you’re talking about. Not that I wouldn’t consider adding a starting pitcher, but the cost in both dollars and player capital is typically high that time of year for starting pitching. So you have to balance that with the impact a reliever can make more often with the impact the guys from within the organization can make.”

Forst also said he wouldn’t rule out adding a position player before July 31, though the A’s have no real open spot and a small bench, and like their current group. The main takeaway: Though things certainly could change in the next five weeks, the team is two games back of the second wild-card spot and currently more a buyer than a seller.