HOUSTON -- Prior to his outing Saturday at Minute Maid Park, Aaron Brooks had not faced the Astros since 2015. But even with three full seasons separating his two most recent starts against Houston, the results looked very similar.

That wasn’t good news for the right-hander, who remains winless against the Astros after yielding five runs over five innings in a 6-0 Oakland loss. It was the first time this season the A’s have been shut out.

It was also the first poor outing by an A’s starting pitcher. Entering Saturday’s game, the group had compiled a 2.41 ERA and allowed just 42 hits over 59 2/3 innings. That included a solid season debut by Brooks, who threw six shutout innings in an April 1 win over Boston.

“Overall, I try not to be too negative,” Brooks said. “Take away a couple pitches that they capitalized on, and I think it was decent. I didn’t really have too much offspeed tonight so I tried to rely on [my] sinker and fastball, and they ended up catching up to a couple. And it went the way it did.”

The fifth inning on Saturday ended both Brooks’ night and the chances for the A’s to keep the game close. A 1-0 deficit widened with two Astros homers -- a two-run shot by George Springer on a 90 mph fastball, and a two-run homer by Michael Brantley, hit off one of 13 changeups Brooks threw over his 91-pitch outing.

“I thought his stuff was real similar to the last time out early on,” A's manager Bob Melvin said. “In the fifth, they just kind of wore him out a little bit, got some guys on base and had some good at-bats off him, like they tend to do. I wouldn’t say it’s a horrible start but we wanted to try to get some innings out of him, obviously, in the stretch we’re in. They did some damage and put a crooked number on him in the fifth.”

The inning began with a walk to the Astros nine-hole hitter, Jake Marisnick, though there was evidence to suggest ball four was actually a strike. Marisnick worked the count to 3-1, and Brooks’ fifth offering looked like it may have hit the low-and-away corner of the strike zone for strike two.

The A’s shrugged off questions about the calls behind the plate.

“That’s baseball,” Brooks said. “It could go either way. My job is to, regardless of what happens, make another pitch after that. I didn’t.”

Added Melvin: “We got a few pitches out of the zone, they got a few pitches out of the zone. It’s tough to say one particular pitch ends up costing you the game.”

Brooks acknowledged fatigue may have been a factor in that fifth frame. He threw 32 pitches in that one inning.

“A little, maybe,” he said. “It’s a little different with the humidity here and stuff here versus Arizona and Oakland. No excuses.”

The A’s have begun their longest road trip of the season, and are also in the midst of their longest stretch without a day off. They opened the non-Japan portion of their regular-season schedule with 18 straight games. Their first off-day is April 15.

It’s too early in the season to start talking about bullpen fatigue, but it’s notable that the A’s entered Saturday’s game with 41 1/3 innings thrown by their ‘pen -- the most in the Majors. And they added three more on Saturday.

Oakland and Houston proved to be the class of the American League West division in 2018, with the A’s qualifying for the postseason with 97 wins, and the Astros setting a club record with 103. But the A’s still are struggling to keep up with their division foe. They lost 12 of 19 to Houston in the season series last year, and they’re 0-2 so far this weekend. In two games with the Astros, they’ve scored two runs.

“You look up and down the lineup, we have a couple guys that are swinging the bat OK, and then quite a few that aren’t at this point,” Melvin said. “Then you come up against a pretty good staff, especially in this ballpark, and it accentuates things a little bit. We’ll get it going.”