Pettitte, who grew up and still lives in the blue-collar Houston suburb of Deer Park, created a frenzy when he left the Yankees to sign with Houston prior to the 2004 season, and the madness grew to Astro-nomical proportions when Roger Clemens joined him a month later.
With Pettitte, Clemens and Roy Oswalt anchoring the rotation, and Lance Berkman, Craig Biggio, Jeff Bagwell and -- for at least a part of his time in Houston -- Carlos Beltran and Jeff Kent bolstering the lineup, the Astros came within a game of reaching the World Series in 2004 and broke through and reached their first Fall Classic in 2005.
Pettitte, who on Friday announced his retirement from baseball, will always be remembered more for winning five World Series rings as a core member of the Yankees dynasty of the late 1990s, early 2000s, but his time in Houston was nothing short of spectacular.
The reaction to his retirement by his former Astros teammates was typical.
"He was a great teammate and an even better person," Oswalt told MLB.com.
Pettitte, who signed a three-year, $31.5 million contract with the Astros prior to 2004, posted a 37-26 record in his three years in a Houston uniform. He went 6-4 with a 3.90 ERA in 15 starts in 2004 before having to undergo season-ending elbow surgery, but he went 17-9 with a 2.39 ERA in 2005 and 14-13 with a 4.20 ERA in 2006.
"The 2004 and 2005 seasons were certainly magical years, and the signings of Andy and Roger on the hometown angle certainly contributed to that, as did obviously their great talent," Astros president of baseball operations Tal Smith said. "He certainly helped anchor a very good pitching staff. He was always very competitive, gave you everything he's got and pitched with a great deal of poise and savvy. He was a joy to watch and had a great career."
Brad Ausmus had the enviable job of handling Pettitte and the rest of the staff.
"He's the one pitcher I want on the mound if we need to win a game to save the human race," he said Friday. "And one of the best teammates I ever played with."
The Astros narrowly missed reaching the playoffs in 2006, and the Astros courted the left-hander following that season and offered a one-year deal for $12 million. Pettitte's camp had a counteroffer of $14 million with an option, but the Astros declined and he wound up signing a one-year, $16 million deal with the Yankees.
"In my opinion, you can trace the demise of the Astros after '06 to not re-signing Pettitte," former Astros manager Phil Garner said. "As we found out, it's extremely difficult to replace him."
While in Houston, Pettitte forged a reputation as a dogged competitor. With his left elbow in tatters in the '04 season, he kept pitching without his best stuff because he said he felt an obligation to live up to the contract he signed with his hometown Astros.
He finally had elbow surgery in '04 and came back strong in '05. Pettitte finished fifth in the National League Cy Young voting (behind Clemens and Oswalt, among others) and went 14-2 with a 1.56 ERA in his final 20 starts of '05, leading the Majors with a 1.69 ERA and a .201 batting average against in the second half.
"For me, the thing that stood out was his willingness to pitch no matter what," Garner said. "That's something a lot of young kids nowadays have to be shown. We coddle kids today and there's probably nothing wrong with that, but in doing that we make them a little bit soft. Sometimes they can't learn how to win when they're not at their best, and that's what Andy did in '04. He was pitching the ball 80 mph and still winning."
The most indelible memory Garner has about Pettitte's time in Houston came during a game in which he didn't even pitch.
In the Astros' memorable 18-inning win over the Braves in Game 4 of the 2005 National League Division Series in Houston, the team sent Pettitte home because of flu-like symptoms. But as the game dragged on and the Astros burned up pitcher after pitcher, Pettitte became antsy.
"He was sick as a dog," Garner said. "He calls me in the 10th inning on one of the trainer's phones and they bring it to me and he says, 'Skip, I can be there in a few minutes if you need me.' I said, 'Andy, you stay home.' About the 14th inning, I felt a tap on my shoulder, and I turned around and Pettitte's dressed and has his shoes on and he looks like death warmed over. But he was here and ready to pitch.
"That wasn't bravado. If I asked him to pitch, he would have pitched and would have performed well."
The Astros have yet to return to the playoffs since Pettitte returned to the Yankees, but his impact on the organization and his teammates was huge.
"Andy was a great teammate, just like Roger," Biggio said. "Both of those guys came in and gave our pitching staff some stability to go along with Roy. He came and took the ball whenever he had to, and was a really good teammate and a good guy, too."
Brian McTaggart is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.