HOUSTON -- An eerie feeling came across A’s manager Mark Kotsay earlier this week when he checked the American League West standings and saw the Astros slumping in fourth place at 10 games under .500.

“It’s kind of scary, right?” Kotsay said ahead of Monday’s series opener at Minute Maid Park. “That’s a good team over there. I don’t think they’ve hit their stride. They’ve gotten some players back. … [Yordan] Alvarez, [Kyle] Tucker, you can go down the lineup. It’s a lineup that can be dangerous, has been dangerous, and probably will be dangerous.”

Kotsay was not buying the early-season chatter surrounding the Astros and whether they might be on the decline. He has seen enough of them over the years and knew better than to count out their pedigree of winning.

Four days later, the Astros are looking like the Astros again, and it came at the expense of a young A’s club that is now falling back to earth after emerging as one of MLB’s surprise teams with its early success, climbing as high as .500 at 17-17 on May 4. Thursday’s 8-1 loss at Minute Maid Park completed a four-game sweep for the Astros (19-25), who leapfrogged Oakland (19-27) for third place in the AL West.

When this 10-game road trip began on May 10 in Seattle, the A’s had a firm grasp on third place and a mostly healthy starting rotation. Seven games into it, three-fifths of their Opening Day rotation (Joe Boyle, Paul Blackburn and Alex Wood) is now on the injured list, and they have dropped 10 of their last 12 games.

Joey Estes -- ranked Oakland’s No. 11 prospect, per MLB Pipeline -- is one of the young starters who has been called upon to fill a rotation spot. Coming off an impressive season debut in which he earned his first big league win, Estes was much less efficient this time out. The 22-year-old right-hander was done in by a six-run third that saw Houston do all of its damage with two outs and balloon Estes’ pitch count to 73.

Estes did not last much longer. Pulled with two outs in the fourth, he allowed eight runs on eight hits, both career highs, with four walks and four strikeouts in 3 2/3 innings.

“He’s not someone that is going to overpower guys,” Kotsay said of Estes, noting that his fastball velocity average of 91.9 mph was down from an average of 93.2 mph in his first start of the year. “But if you don’t locate, you can’t get good hitters out. That was an example tonight. We also gave up seven or eight free bases. You give good teams extra bases, it’s going to be a challenge to limit their runs.”

Estes said he felt fine physically despite the decreased velocity, attributing his short outing to falling behind in counts early and often. Making just his fourth Major League start, Estes is now learning on the fly at the big league level. Thursday gives him something to focus on before his next outing, likely Wednesday against the Rockies.

“You take a lot from these outings,” Estes said. “Even more than the outings that you go six innings and no runs and everything goes perfect. You learn from these, get through it and move on to the next one.”

While the rotation is in a bit of turmoil as the A’s are still mulling their options for Friday’s starter, with long reliever Kyle Muller the likely option, hitting is the main issue right now. Oakland was held to just four runs in four games against Houston.

Much of the club’s early-season success was built on an ability to hit the long ball. The A’s are tied for the fourth-most home runs (55) in the Majors and entered Thursday’s game leading MLB with 51.2 percent of their runs scored via homer this season. They went homerless against the Astros and now head into a three-game series in Kansas City set to face the Royals’ top three starters in Cole Ragans, Seth Lugo and Brady Singer.

“Coming off the Seattle series, I thought we swung the bats well,” Kotsay said, pointing out the A’s 13 runs scored in three games against the Mariners. “We got here and we got dominated. We’ve got to go back to the drawing board and figure out how to get the offense going again. We’re going into Kansas City and those guys have been throwing the ball well. We’ve got our work cut out for us offensively. We need to do a better job.”