Buster Posey acting all grown up

SAN FRANCISCO -- If you would have walked into the clubhouse and seen catcher Buster Posey after Game 4 of the National League Championship Series here Wednesday night, you would have immediately thought the San Francisco Giants had lost.

As Puff Daddy and The Notorious B.I.G. played in the background and a few teammates smiled and sipped on a celebratory beer, the 23-year-old rookie quietly rocked back and forth in the leather chair in front of his locker, his face as expressionless as a mime's. There was no smile. No bobbing of the head to the beat. Nothing.

A few minutes earlier, he had dug in against Roy Oswalt, one of the best pitchers of this generation, and done what most of the 43,515 screaming, towel-waving fans at AT&T Park expected him to do: deliver.

He ignored the expectations, shut out the pressure of the postseason spotlight and performed with the poise of a major league veteran. Despite having been in the bigs for less than four months, despite going 0-for-3 against Oswalt three days earlier, Posey connected on the biggest hit in the biggest game of his young career.

It wasn't easy. After falling behind 0-and-2, the rookie fouled a pair of pitches off and then -- in one of those moments Giants fans will undoubtedly remember -- laced a long single to the right-field corner, pushing Aubrey Huff from first to third and setting up Juan Uribe's game-winning sacrifice fly minutes later.

"What an at-bat," Huff said. "He just willed that ball into right field."

Afterward, Posey sat there with the excitement of someone who was sitting in the lobby of the dentist's office.

"That's just the way he is," teammate Mark DeRosa said. "He has the talent and ability of a 23-year-old with the mind and poise of a 33-year-old. He's just a special talent. I don't ever remember anyone like him."

Before Wednesday night, Posey had been all but forgotten in this series. After carrying the Giants for the second half of the season and posting the seventh-best average for a rookie against Atlanta in the Division Series, Posey was a mere 1-for-11 in the NLCS entering Game 4. Huff said people had been coming out of the woodwork to help him with his swing.

"There were a million people saying try this or try that," Huff said. "But that kid, he doesn't need it. He should be the one giving the advice because he's got one of the best right-handed swings in all of baseball."

On Wednesday night, it showed. By the time the 3-hour, 40-minute seesaw affair was over, Posey would go 4-for-5 with a pair of doubles and two RBIs in a 6-5 win for the Giants that has San Francisco one win from the World Series. More importantly, he was in the middle of nearly every key Giants rally and arguably their biggest defensive play of the night as well.

He was the first San Francisco Giants rookie to ever have four hits in a postseason game and only the fourth catcher in baseball history to record four hits and two RBIs in a playoff game.

"He did all the damage for us, really," Giants manager Bruce Bochy said.

So on a night when there were many heroes in black and orange -- Juan Uribe, Pablo Sandoval, Huff and Brian Wilson, to name a few -- it was the 23-year-old catcher whom everyone couldn't stop raving about after the game.

"The way he approached that last at-bat, you would have thought he had owned Oswalt," former Giants great Will Clark said. "His confidence for someone with such little experience is remarkable."

Posey, of course, isn't impressed. When asked after the game if he had a chance to digest the magnitude of what he had accomplished by carrying his team to victory, he replied, "I helped the team win. I guess that's how I digest it."

When a reporter asked Posey if he understood that it was an epic night for any player in a postseason game, the kid replied, "Well, thank you."

It isn't arrogance. Or shyness. It's simply the way the former first-round draft pick is wired and the reason he's able to accomplish as much as he has as early as he has.

When Philadelphia Phillies outfielder Shane Victorino stepped up to the plate in the first inning of Game 1 on Saturday, he told the Giants catcher that it wasn't too long ago that he was a stud at Florida State and the Phillies were facing off against the Seminoles in spring training. Posey just giggled and said, "I remember."

"I was complimenting him on how far he's come and how he's growing as a catcher," Victorino recalls. "Obviously, he has a lot of hype around him and everyone expected him to do this. But to keep doing it and keep excelling, I tip my cap to him."

On Wednesday, Giants fans found themselves in the same position seemingly every couple innings. In the first, his two-out single scored Freddy Sanchez to give San Francisco a 1-0 lead. Two innings later, he hit a two-out double that scored Huff to put the Giants up 2-0.

Then, when the Phillies came roaring back in the fifth inning, Posey made one of the key defensive plays to limit the bleeding. With runners on second and third with one out, Victorino singled to center and Aaron Rowand came up throwing in an effort to cut down Carlos Ruiz at the plate. With Ruiz bearing down on Posey, Rowand's throw landed about a foot short of the catcher's glove. Yet Posey dug the ball out of the dirt like a first baseman and, in one motion, applied the tag to Ruiz's leg for the second out of the inning.

"That's the toughest play in baseball," said Bochy, a former major league catcher. "You've got to handle the throw, you've got the runner bearing down on you, and you've gotta keep your focus and make sure you secure the ball. There's not a tougher play."

"What a pick that was," Huff said. "If that run scores, I'm telling you, this is a different ballgame. We might be looking at 2-2 and facing Roy Halladay [on Thursday]."

Posey also doubled in the seventh and could have scored the potential game-winning run but was stranded on third when Sandoval grounded into an inning-ending double play. It didn't matter. Though the Phillies scored once in the eighth to tie the game at 5-5, Posey was due up in the ninth. And he didn't disappoint.

Now, instead of the series being tied at 2-2, the Giants are up 3-1 on the two-time defending NL champs with their ace, Tim Lincecum, scheduled to pitch Game 5. The offense scored more than four runs for the first time since Sept. 25, and the baby-faced rookie cleanup hitter appears to have found his stroke. By all accounts, for the time being, life is good. No matter what the postgame expression on Buster Posey's face might suggest.

Wayne Drehs is a senior writer for ESPN.com. He can be reached at wayne.drehs@espn.com.