"Stuff-wise, I thought he was OK," said Josh Donaldson, who went 0-for-3 with a walk. "I don't think it was anything special. But he changed speeds well and pitched to his game plan."
He also recorded a 5-1 victory against an A's club that had won five in a row against the Astros before dropping each of the last two in Houston this weekend.
McHugh was brilliant, even if he wasn't dominant.
"Throwing the offspeed stuff for strikes, that was basically it," said catcher John Jaso. "That and getting ahead.
"I thought he was pretty good. He kept people honest with his offspeed stuff, a lot like Tommy [Milone] did. Tommy was throwing his curveball for a strike and his changeup for a strike, too. When you don't have 96 [MPH] in the tank, that's really important to do."
Milone was just as effective with his offspeed pitches, minus a changeup he left up to Jonathan Villar, who hit it for a two-run triple in a four-run seventh inning. The Astros hadn't scored since the third.
The lefty scattered just four other hits with two strikeouts and two walks through a season-high 6 2/3 innings. By day's end, he had four earned runs to his name, as Dan Otero offered up the first home run of his career to Jose Altuve following Villar's triple.
Otero had gone 63 2/3 innings without allowing one, the most innings pitched among active players without surrendering a homer.
"I still shouldn't have thrown that pitch. I just left it in a little bit," Otero said. "Just unfortunate, especially allowing one of Tommy's runs."
"Tommy pitched great," manager Bob Melvin said. "Very few balls were hit hard. He pitched as well as we've seen him in a while."
Oakland collected a combined 39 hits in its first three games in Houston, but reached base just six times in McHugh's second start of the season for the Astros.
After Jed Lowrie's one-out single in the first, the A's drew three walks through the first three innings, before McHugh proceeded to retire 19 in a row. With two outs in the ninth, he hit Brandon Moss in the foot -- a play which was corrected after a replay review -- and Moss stole second before scoring and breaking up the shutout on a single by Alberto Callaspo.
Lefty Raul Valdes got pinch-hitter Craig Gentry to fly out to center for the final out of the game -- the first this season in which the A's lost by more than three runs.
"That was an outstanding performance," Astros manager Bo Porter said. "When we sent him out there in the ninth, it was with the complete hope that he was going to be able to finish what he started. That was tremendous, attacking the strike zone with all three of his pitches. To pitch that well against a really good-hitting Oakland lineup speaks volumes to Collin and the way him and [catcher Carlos] Corporan worked today."
With the loss, the A's fell to 9-7 during this stretch of 19 consecutive games against American League West competition, with a three-game set against the host Rangers next on the schedule.
"It's frustrating," Donaldson said. "Tommy pitched a pretty good game today, too, and you always want to get your starter a win.
"You have to flush it going into the next series, and we have a big series coming up. We want to beat those guys."