OAKLAND, Calif. — Still donning a full, dirty uniform while most of his teammates had changed and showered, Alex Bregman placed both hands on the bill of his cap. His tone was hushed, almost somber in a clubhouse that was anything but.

A reporter asked for a recollection of the at-bat that won a game, Bregman's fourth-inning grand slam off A's reliever Liam Hendriks. With the bases loaded and two outs, the third baseman looked for a fastball to drive. Instead, Hendriks hung a slider.

Bregman boomed it to left center field. He took two steps forward and flipped his bat. The lumber spun twice and landed near the field. Bregman broke into the trot that ended a game and prolonged Houston's 10-game winning streak.

"I think I've just been terrible, honestly. I haven't been good at all offensively," Bregman said after Tuesday's 9-1 victory.

"Today was a step in the right direction, but I just haven't performed how I would have liked to. The one thing that I like is the win column and I'm glad we're winning games. I'm happy that we've been winning, but I have to get a lot better."

Bregman finished the game 1-for-5 with those four RBIs. Since returning from a two-game absence due to a hamstring injury, he is 2-for-12.

Still, after 15 games, he is hitting .302 with an .869 OPS. The numbers are satisfactory, especially given the hamstring injury that disrupted his rhythm.

"I think I've just been terrible, honestly," Bregman said. "I haven't been good at all offensively."

Delivering such a harsh self-assessment is Bregman's forte. The man is never satisfied and, if he is, will hardly acknowledge it publicly. Bregman is one of two Astros hitting .300 with at least 50 at-bats. His on-base percentage is .397, highest among the Astros' regulars.

"I'm hitting the softest .300 in baseball," Bregman said. "I need to start driving the baseball."

Just five of Bregman's 16 hits have garnered extra-bases. Bregman bemoaned his inability to hit fastballs — a rarity in his short major league career — and blamed it on a mechanical tweak he is still working through.

It's why he sat fastball against Hendriks in the fourth-inning at-bat. Bregman thought it would come. He is being fed a steady diet of four-seamers — 60.3 percent of the pitches he's seen, to be precise — because, Bergman said, he cannot drive them adequately.

Bregman is swinging and missing at a 10.2 percent rate against fastball, around his career average. However, he's getting under the baseball 38.5 percent of the time, a noticeable spike.

The cause, Bregman said, is how he loads himself to hit. Tuesday, he implemented some tweaks with his setup and it worked.

"How I'm loading is different," Bregman said. "I was putting myself in a bad position to hit and getting beat by heaters I never get beat by."

"I'm getting exposed by fastballs and I shouldn't be. Basically, just horrible at the plate."

In a clubhouse containing well-compensated crushers who expect premier performance every day, Bregman's self-expectations sit near the top. His teammates adore the obsession, even if they find little fault with what he is producing.

"I think Alex could hit .350 and he'd still be in his own head about trying to improve something or get better," said Josh Reddick, who hit a two-run home run Tuesday. "And you can't take that away from him because the will to be perfect in him is there every day. He wants to go 4-for-4 every night and when he doesn't he's mad."