SEATTLE -- Kendall Graveman's first outing at T-Mobile Park since the Astros traded for him to bolster their bullpen a month ago couldn’t have gone any worse Tuesday night. Especially considering the guy who ruined the night for Graveman and his team.

Abraham Toro, who was one of two players traded to the Mariners on July 27 in exchange for Graveman and pitcher Rafael Montero, slugged a grand slam in the eighth inning of a scoreless game to lift the Mariners to a 4-0 win over the Astros.

“Dammit, that was a tough game to lose,” said Astros manager Dusty Baker, whose team leads the A’s by five games in the American League West.

With the bases loaded, Graveman missed with a sinker before getting Toro to swing under two sinkers to get ahead, 1-2. But he couldn’t put him away. Toro worked the at-bat, fouling off three pitches, before turning on a 96.8 mph sinker at 2-2 and sending it 413 feet into the seats in right-center field.

“He did a good job getting the barrel there,” Graveman said. “He’s put together some good at-bats against us. He’s a good player. For me personally, I wouldn’t change anything really about that at-bat, maybe a little bit further in on that last pitch. Tip your hat. If I don’t walk a guy or hit a guy, I’m not in that situation and it doesn’t come down to that.”

Graveman faced the top of Seattle’s order to start the eighth and walked J.P. Crawford. The right-hander allowed a one-out single to Kyle Seager and hit Ty France with a pitch to set the stage for the switch-hitting Toro to be the hero.

“When the inning started, I remember telling the guys, ‘Hey guys, I'm gonna have that big at-bat,’” Toro said. “And then I got that big at-bat and I just took two really big swings, so I was under the baseball, and after when I had two strikes, and I was just trying to be short to the ball, trying to get a sac fly, and then ended up hitting pretty good and it paid off.”

Graveman said returning to pitch on the mound in Seattle didn’t feel too awkward, but admitted the Mariners’ familiarity with him probably played to their advantage. He’s given up six earned runs in 12 1/3 innings with the Astros, and five of them have been to his former teammates.

“There’s a familiarity that goes a little bit deeper than just looking at numbers and iPads and things like that,” Graveman said. “I’ve just got to execute. That’s all it boils down to. I’ll be better for this outing and I think I’ll learn from it and grow from it and continue to move forward.”

It appeared Graveman had struck out Crawford to start the inning, but a 3-2 pitch at the bottom of the zone was called a ball. Astros catcher Martín Maldonado caught the pitch and spun around in frustration, hoping to get a strike call. 

“Evidently, Maldy thought it was a strike because I’ve never seen him react like that to a pitch,” Baker said. “That’s what got them kind of started.”

Graveman said the pitch could have gone either way, adding that he shouldn’t have even allowed the at-bat against Crawford to get to a three-ball count. His troubles started long before Toro came to the plate.

“Even the best of them get hit sometimes,” Baker said. “That was pretty evident tonight. We all know he’s one of the best. We just got beat tonight.”