While Clemens has those 341 lifetime victories and Pettitte went into Wednesday night's game with 14 postseason wins, one shy of the record held by Atlanta's John Smoltz, Oswalt has an 83-39 record since he came up to the Astros for good during the 2001 season.
He was 19-9 in 2002, 20-10 in 2004, and 20-12 this past season when Clemens won 13 games and Pettitte won 17.
But he's the forgotten man behind the other two, Garner said.
"He's a second-time 20-game winner and you don't hear much about it," Garner said about Oswalt. "If it happened to anybody else, it would be all over the place. But Roy is not a self-promoter. He's very laid back and that's not a show he puts on. He's very comfortable being in the back room. He doesn't need to be out front. He doesn't have to have a lot of the spotlight.
"But then you have great personalities like The Rocket and Pettitte, who have done wonderful things, so it all naturally gravitates in that direction."
Within the sandwich of the three starters, Oswalt will certainly give the Cardinals a much different look on Thursday night from the left-handed sinkerball offerings of Pettitte.
A native of Mississippi, Oswalt is listed at 6-foot-0, 185 pounds and throws with his entire body like Ron Guidry, the left-handed former Yankee once nicknamed "Louisiana Lightning" for the whip-like motion he used to throw his 98-mph fastball.
"It's so different, Andy pitching and me pitching," Oswalt said. "Andy is left-handed, throws different pitches than I do, coming from a different angle. And I'm sure they're probably going to have a different lineup than they will against him. With me, they'll try to put as many lefties as they can against me in the lineup."
As far as working with The Rocket, Oswalt called the certain future Hall of Famer "one of a kind, for sure."
"His mentality on the days he pitches is totally different from every other day," Oswalt said. "He gets me to look at the replays, and if a guy gets a hit on a good pitch he threw, he wants to know if he did anything wrong. Anything I can pick up. I try to limit my walks through what I call 'The Rocket Tunnel' as much as possible, because every time I go through it, he's asking me different questions about different things and I don't want to give him the wrong answer."
Last year in the NLCS against the Cardinals, Oswalt was the Game 4 starter in Houston's Minute Maid Park. He lasted six innings, allowing five runs on eight hits, including a two-run first-inning homer to Cards slugger Albert Pujols. The Astros won that game, 6-5, on a Carlos Beltran eighth-inning homer, but lost the series in seven games.
Between the last two postseasons he's 2-0 and beginning to build his own playoff resume. He was the Game 3 starter and winner over Atlanta in the NL Division Series at Houston on Saturday, and he'll try to carve more of his own place on Thursday night.
"I think part of the experience of playing in the postseason is learning how to handle all the notoriety," Garner said. "Normally we come to the ballpark and you might talk to a couple of reporters. One of the things you have to learn is that when you get here these things happen for a couple of hours now. In Roy's case, he's learned that he does what he has to do, but what he really does is pitch."