Girardi dropped Teixeira to sixth in New York's batting order, with Robinson Cano and Nick Swisher hitting fourth and fifth, respectively, against Red Sox right-hander Daisuke Matsuzaka.
"Swish is just swinging really well," Girardi said. "We're going to put Swish in the fifth [spot], and it just keeps some space between our left-handers with the two switch-hitters between them. I love the way Swish is swinging the bat."
Swisher is hitting .393 (22-for-56) with four homers and 14 RBIs over his last 15 games, hitting safely in 14 of those contests. Teixeira, meanwhile, is playing just his third game since returning from a left calf strain and heard boos after several of his at-bats on Tuesday.
"I've always said it, I've been booed since the first month I got here," Teixeira said. "When you don't perform well, you boo yourself. No one's more upset about it than I am. I'm a fan, too. Georgia Tech lost by  points at home to Middle Tennessee State last week and I was not happy about that game. I know what it's like to be a fan."
Girardi acknowledged he isn't sure what to expect out of Teixeira, which could bear watching as the Yankees progress deeper into October.
"We were fairly consistent when guys are here for a period of time, but when guys aren't and they're coming into the lineup, you have to see where people are at," Girardi said. "Sometimes you have to shuffle things around, but it's nice to be getting all our pieces back where we have our switch-hitters and we can break up the lefties. That's a good thing."
Girardi added that he remains committed to batting Alex Rodriguez in the No. 3 spot. Rodriguez has eight hits in his last 38 at-bats, going 2-for-5 in Tuesday's 4-3 win.
"The one thing is, he has been getting on base," Girardi said. "That's important in front of Robbie Cano; we want those RBI opportunities and guys are driving him in. At any point, we know the damage that he can do."