HOUSTON -- The frustration in Alex Bregman’s voice was evident, but he could have been speaking for the entire Astros offense -- an offense that’s been shorthanded all season and clearly isn’t getting enough production from some of its middle-of-the-order bats.

After suffering their first shutout loss Tuesday night, the Astros didn’t score Wednesday until Bregman rocketed a two-run homer into the left-field seats in the eighth inning of a 4-2 loss to the Giants at Minute Maid Park. The 2023 Astros remain an enigma, going 5-1 on a road trip to Atlanta and Tampa Bay before coming home and losing four of six to the Phillies and Giants.

“At home here, we got a couple of pretty good games [pitched] against us,” Astros manager Dusty Baker said. “We had them on the ropes a couple of times early in the game, and we just didn’t come through with the big hit. It was tough on our offense the last couple of days.”

In the Astros’ last seven games (3-4), they’ve slashed .187/.246/.269 as a team with six doubles and four home runs, averaging 2.3 runs per game. Bregman’s homer was his first at Minute Maid Park this season.

“It felt good to square the ball up, but overall we’re not doing enough offensively right now,” Bregman said. “We need to do a better job of swinging at better pitches and damaging pitches over the middle of the plate. I think we’ll all get together here before the game on Friday and kind of go through things and see where we can improve. I know how good of an offense we have here and look forward to showing it.”

Having played much better on the road (8-4) than at home (8-11) this year, the Astros’ next nine games will be away from Minute Maid Park, beginning with Friday’s series opener against the Mariners in Seattle. It’s a rematch of last year’s AL Division Series, which the Astros won in three games decided by a total of four runs.

The Astros should get two key pieces back in their lineup during the road trip. Michael Brantley, who had shoulder surgery last June, is nearing the end of his rehab assignment at Triple-A, and center fielder Chas McCormick is winding down his rehab stint at Double-A. They both could be back by Tuesday.

“I think it’ll be great to get those guys back,” Bregman said. “I have confidence in every single person in this clubhouse. We haven’t gotten going yet, but we will. Confident in it.”

Bregman is in a 3-for-29 slump in his last eight games, while All-Star right fielder Kyle Tucker is 2-for-22 in his last six games. Tucker has played all but four innings this season in right field, and giving him a day off has been near impossible while McCormick is out. Bregman has played every inning of every game at third base.

“There might be some fatigue, but we’re playing the best lineup we can play considering we’re off every six days,” Baker said. “Those are the days you’ve got to get your rest. We’re trying to get to the point hopefully we get Michael [Brantley] back soon. We’ve been wanting to rest Tucker, but he’s the best right fielder in baseball, probably, and definitely the best right fielder we have. There’s probably more mental fatigue than physical fatigue.”

Meanwhile, first baseman José Abreu, the Astros’ big offseason acquisition, is mired in the longest home run drought of his career and is slashing .232/.267/.264 for the season with only 13 RBIs. Among his 29 hits, 25 have been singles.

“We just need to do a better job offensively,” Bregman said. “We haven’t really strung anything together. A lot of quick innings for the opposing pitching staff. I think all of us know that.”

While the offense has struggled, the Astros’ vaunted pitching staff has been decimated by injuries. Houston lost starters José Urquidy (shoulder) and Luis Garcia (elbow) to injuries that landed them on the injured list in successive days on Sunday and Monday. Ace lefty Framber Valdez did his part Wednesday, striking out eight batters and allowing two runs in six innings for his sixth consecutive quality start. Despite his 2.60 ERA and 1.16 WHIP, Valdez is 2-4 (the Astros are 2-5 in games he’s started because of poor run support).