OAKLAND -- Divisional play continues to derail the A's, who suffered a 6-3 loss to the Astros in Tuesday's series opener at the Coliseum.
Gifted a one-run lead in the first inning by way of a wild pitch, the A's quickly found themselves in a hole that would only grow deeper. Evan Gattis was the culprit, totaling a career-high five RBIs under the watch of Oakland starter Daniel Mengden, who issued a season-high four walks.
Gattis' go-ahead, three-run homer in the second capped a four-run inning that began with a home run from Carlos Correa. Mengden, who yielded just six home runs over his first 12 starts, has matched that total in his last two outings.
"He's missing in the middle of the plate when he's missing, and he's not getting ahead in the fashion he was earlier," A's manager Bob Melvin said. "He'll get back to it. He's just going through a little bit of a rough patch."

Lifted with two outs in the fifth following Gattis' two-run double, Mengden was on the hook for six runs and eight hits in the loss, which dropped him to 0-5 with a 6.94 ERA in seven career starts against the organization that drafted him in 2014.
"It comes down to not executing and not getting strike one," said Mengden, who posted a 1.51 ERA in six May outings. "I'm not missing by much. I feel like a lot of it is around the zone, which is where I want to be, it's just not exactly where I want to be. The mistakes I do have, I'm not getting away with it."
The A's fell to 10-22 against American League West opponents, including 1-6 against the Astros. In contrast, they've played to a 24-11 record against all other teams.
After defeating Houston, 8-1, in their first meeting of the year, the A's have been outscored 49-11 over the last six contests. Astros right-hander Lance McCullers held them to five hits over seven innings -- three of them doubles off the bat of Matt Chapman, tying an Oakland single-game record.
Mark Canha notched a two-out RBI single in the eighth to make it a 6-3 game, but the A's left the bases loaded, finishing 1-for-8 with runners in scoring position.

"We know we can hang with them, we just have to keep grinding," Chapman said. "I think we're all aware of it. We know how good our division is. Our division is really good. There's no easy night. Every game's been a battle, and I think we've been in every game, and I think we just need to get that late little push to get on top."
Chapman was hit by a pitch in the eighth and underwent X-rays on his left hand that were negative. He's 14-for-34 this month.
"It's a little swollen, but I think it's because it was a pretty good shot," Chapman said. "But it feels like I can move my hand and I feel strong, so I'm not worried about it.
"Seems like those kinds of things happen to you after you hit a few balls good."

MOMENTS THAT MATTERED
The A's were in position to strike with two outs in the fourth, when Chapman doubled and Canha and Stephen Piscotty drew walks against McCullers. Jonathan Lucroy worked a 2-1 count against the right-hander but sent a curveball into the ground for an inning-ending groundout. McCullers retired 10 of his final 11 batters.

SOUND SMART
Marcus Semien played in his 461st game at shortstop for the A's, tying Alfredo Griffin for seventh-most games at the position in Oakland history. With five more games, he'll pull into a tie with Cliff Pennington.
HE SAID IT
"Definitely been working on a few things, and I feel like I've been really good about my pregame work and my routine, just trying to stay diligent with it, and I think it's allowed me to be more consistent. We watched some film, and we saw when I was going well I was really direct to the baseball and there wasn't any wasted movement. I think when I was struggling a little bit, my swing was getting a little long, so just trying to be direct to the baseball." -- Chapman

UP NEXT
Right-hander Paul Blackburn, who twirled six innings of one-run ball in his season debut against the Royals on Thursday, will be back on the mound Wednesday for a 7:05 p.m. PT start against the Astros. Houston will counter with right-hander Gerrit Cole, who is 7-1 with a 2.16 ERA.