Girardi left Angel Stadium kicking himself after Morales belted Damaso Marte's 3-0 fastball over the wall for a three-run homer, blowing open what ended as an 8-4 Angels victory.
As the Yankees prepared for their flight back to the East Coast, Girardi said that he had almost walked Morales and had David Robertson go after Juan Rivera instead -- especially after Marte threw three pitches out of the zone.
"I screwed up, in a sense," Girardi said. "I could have done it. Your first instinct sometimes is your best instinct."
The at-bat developed as Marte looked in to Morales with Torii Hunter at second base and Hideki Matsui on first base, with one out. Catcher Francisco Cervelli put out his right hand and Marte threw an intentional ball wide of the plate.
Then, the Yankees reconsidered, with Girardi taking about four steps out of the dugout and third baseman Alex Rodriguez charging to the mound to make sure everyone was on the same page.
"We thought about walking him and bringing in Robby to face Rivera," Girardi said. "I probably should have stuck to my first instinct. At times you look at matchups and you look at things. The matchups were about even for both of them."
Ready to pull the trigger and have Robertson finish the intentional walk to Morales, Girardi wavered. Cervelli also thought the intentional walk might still be in order, going out again to stall for time so Robertson could finish warming up.
Instead, Marte went back to work, with Hunter stealing third on the 1-0 pitch. That fastball and the next one missed, and Marte was throwing a 3-0 cookie down Broadway -- a pitch Cervelli wanted outside.
"That's what they told me. I've got to do it," Cervelli said. "They changed their mind. Maybe we could have thrown a better pitch in that count, especially on 3-0. We didn't have to come in the middle of the plate. Maybe that's my mistake."
Girardi regretted not making that pitch an intentional free pass.
"He got to 3-0 and I could have put up four [fingers] again," Girardi said. "I probably should have put up four there. ... Cervy knew what we were trying to do. We told Cervy, 3-0, you've got to be smart. Don't give in."
The switch-hitting Morales has had more success in his career batting left-handed than right-handed, which was why the Yankees thought about keeping the original matchup.
"It's a switch-hitter, you know," Marte said. "I know how to pitch Morales, but three balls and no strikes, he's waiting for a fastball. I threw the fastball and he hit it."
Across the field, Angels manager Mike Scioscia sure wasn't complaining.
"We like the matchup [against Marte]," Scioscia said. "They had a right-hander ready in the bullpen, and that's why we had him hitting 3-0. He's become a much better hitter from the right side, even though statistically it hasn't shown up this year. He got a pitch he could handle and drove it."
Girardi said that he is pretty good about quickly wiping clean such things -- he couldn't recall another instance where he left the ballpark second-guessing himself.
But until the Yankees touch down at Baltimore-Washington International Airport, Girardi will certainly have something other than the in-flight movie to occupy his attention.
"You have to turn the page and move on, but obviously as a manager there's going to be moves that you think about," Girardi said.
Bryan Hoch is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.