In the 2001 Fall Classic, the Diamondbacks hit Andy Pettitte like they knew what was coming. John Iacono/SI

Andy Pettitte still carries emotional scars from 2001. He knows there's nothing he can do to change it. He's well past that.

But when he lets himself think about the fall of 2001, when he reflects on Game 6 of the World Series, one horrible, recurring thought keeps barreling its way into his head.

"Basically," Pettitte says now, "I feel like I cost us a World Series ring."

Pitchers can do a lot to win or lose a lead, a game or a series -- even a World Series. Pettitte helped the Yankees win four championships. He was one of Joe Torre's go-to guys. Before 2001, Pettitte was 2-1 with a 3.82 ERA in six World Series starts. In his career, he's 6-0 in the American League Championship Series.

But against the Diamondbacks, a little old-fashioned baseball skullduggery did in Pettitte in both of his starts -- and that was the undoing of the Yankees.

Pettitte was tipping his pitches.

First in Game 2, and then to disastrous effect in Game 6 (a game in which the Yankees could have clinched), Pettitte was unconsciously letting the Diamondbacks know what was coming. He was unintentionally broadcasting his pitches for all to see and hear. And the Diamondbacks, who won 15-2 to force a Game 7 they would eventually win, were watching and listening.

"To tell you the truth, I don't think it even entered my mind at first," said Pettitte, who signed with the Astros this offseason. "But as soon as someone came up to me [after the Game 6 debacle] and told me that I might be doing it, I knew it. I knew they had me."

Tipping pitches is a problem as old as infield dirt. It's one that never seems to go away.

Oakland's Barry Zito has been struggling this season, and a lot of people think it might be because he has been tipping his pitches. The Yankees' Jose Contreras recently was sent down to the minor leagues, and one of the problems he might have is that, somehow, he's letting hitters know what's coming.

Arizona lefty Randy Johnson, the co-MVP of that 2001 World Series, altered his delivery at the start of the season because he was afraid he might be tipping. Even during that Fall Classic, there was some talk that the Yankees knew what Johnson was going to throw -- though the Yanks couldn't do anything about it.

The Mets' Tom Glavine used to flare open his glove as he stepped toward home plate, a sure sign a changeup was coming. Right-hander John Thomson of the Braves used to pop his left index finger out of his glove and point it upward before his changeup.

Moises Alou smacked two homers off Orel Hershiser in the 1997 World Series. Alou later told reporters he knew what was coming because of how Hershiser held his glove.

But if you're throwing it middle of the plate, he's not tipping pitches. They're hitting bad pitches  -- Burt Hooton

The tip a hurler gives is often too subtle for most fans to see -- a finger that's a little askew, a glove that is slightly more open, a hitch in a stretch motion, a facial expression. The problem for pitchers is that hawk-eyed players on the opposing team can catch just about anything. And if they notice that, say, the pitcher's glove is not as wide open on a fastball as it is on something off speed, then they'll tell everyone on the team what to expect. Then the pitcher's in a world of trouble.

The Cardinals' Jim Edmonds is notorious for being able to pick up on these signs. Atlanta Braves pitching coach Leo Mazzone says Chipper Jones and Marcus Giles are good at it, too, and they share their knowledge with the rest of the Braves.

Still, not all hitters want to know what's coming. Houston's Craig Biggio, who just crossed the 2,500 career hit threshold, is one of them.

For one thing, Biggio says, what you see from the bench and what you see from the batter's box are two entirely different things. So sometimes the hints are just no good when a hitter digs in. Biggio said he tends to psyche himself out if he knows what's coming, swinging at the pitch no matter where it is.

"And sometimes," Biggio says, "it might be a guy throwing something you might not want to know about."

Former big league pitcher Burt Hooton, now the Astros' pitching coach, doesn't pay much attention to whether his guys are tipping pitches. When he played, he would wriggle his hand around in his glove just to keep the hitters guessing which grip he was using. And if he felt like a hitter was sitting on a pitch he shouldn't know anything about, he'd knock the batter off the plate with something high and hard.

That's not to say that Hooton won't help one of his pitchers once someone points out a potential problem.

	MAILBAG Comments, questions or obviously unfounded criticism? To e-mail Donovan, use the form below. Your name: Your e-mail address: Your home town: Enter your question:

"If you think he's tipping, you get it fixed," Hooton said. "But if you're throwing it middle of the plate, he's not tipping pitches. They're hitting bad pitches."

That, of course, could be the real problem with Contreras, Zito and many others. It might not be that the hitters know what's coming. It might be simply that what's coming is too hittable.

"If you're locating your pitches," Mazzone says, "it doesn't matter."

Still, tipping pitches can be a serious, even debilitating problem, as Pettitte knows. In the 2001 Series, the Diamondbacks first picked up on Pettitte's pitches in Game 2, when they knocked him around for four runs in seven innings. In Game 6, the Diamondbacks jumped on him from the start, blasting him for six runs in the first two innings.

During an international broadcast of Game 6, ESPN analyst and 1984 Cy Young winner Rick Sutcliffe noticed that Pettitte was double clutching when he set from the stretch every time he threw his fastball. Though no one will say if that's what Pettitte was doing, it's clear he was doing something the Diamondbacks picked up on.

Pettitte has since fixed the flaw. But those scars remain.

"All you can say is, if a guy is tipping pitches, you just hope he and the pitching coach can work on it, look at some video or whatever, and see it," Pettitte said, "before you screw up in a World Series."

John Donovan is a senior writer for SI.com.