It is the same, because the jerseys and stadiums and fan bases haven't changed, because the same managers control things from the dugout, because the stakes are identical. When the St. Louis Cardinals host the Houston Astros on Wednesday night at Busch Stadium, the National League pennant will be at issue, just as it was last year in this same stadium, just as it was last year at this same time, just as it was last year between these same two teams.

"It's classic baseball," St. Louis Manager Tony La Russa said. "The winner's in doubt. That's why you play."

But it will be different, too, because the man who will throw the first pitch for the Cardinals, Chris Carpenter, spent the exhilarating series of a year ago watching from the dugout with nerve damage in his right biceps. It will be different, too, because the man who will throw the first pitch for the Astros, Andy Pettitte, had already had surgery on his left elbow by the time the 2004 series began, and he joined Carpenter as a spectator.

Go through the lineups that will take the field for Game 1 of the National League Championship Series, and there are nearly as many differences as there are similarities. These two teams have undergone changes, both fundamental and subtle, all designed to reach this same point in the postseason.

"Organizations like ours, like Atlanta, like the Cardinals, there are similarities to winning organizations," Houston General Manager Tim Purpura said Tuesday. "You have that focus that it's about winning, only winning. You have to have higher expectations than other people. And sometimes, you have to flush guys out of your system that might not buy into it, that might put their stats first, rather than winning. In those types of organizations, guys like that don't last, and they kind of self-select themselves out, and you end up being able to win on a consistent basis because you keep the guys who buy into that."

So even in the wake of their dramatic, back-and-forth, seven-game series of a year ago -- won by the Cardinals, who came from behind to beat Houston's Roger Clemens in the finale -- both teams made adjustments, by design and not.

A year ago, Houston center fielder Carlos Beltran used the NLCS as his audition for free agency, hitting four homers and becoming a star. This year, he played for the New York Mets and will spend this week out of the playoffs, out of sight and mind, because a rookie named Willy Taveras has stepped into his spot and redefined it.

A year ago, veteran Jeff Kent was the Astros' second baseman, versatile Craig Biggio manned left field and stalwart first baseman Jeff Bagwell was healthy and productive. This year, Kent signed with the Los Angeles Dodgers, Biggio moved back to second base, a rookie named Chris Burke played the bulk of the games in left and Bagwell was reduced to the role of pinch hitter because of injuries.

The wholesale changes fundamentally altered the Astros, and it took some time to adjust. They began the year 15-30, and Purpura held a meeting to tell them: "We're not going to blow this thing up and rebuild. We believe in you guys." First baseman-outfielder Lance Berkman came back from a knee injury, and third baseman Morgan Ensberg developed into what La Russa called "one of the best producers in the league." And the Astros became defined by the front three of their rotation: Pettitte, Roger Clemens and Roy Oswalt, who combined to go 50-29 with a 2.43 ERA.

"We're different," catcher Brad Ausmus said. "We have a healthy Andy Pettitte, which certainly helps. We also don't have Jeff Kent, Carlos Beltran and a healthy Jeff Bagwell. Now our reputation starts and ends with our pitching, whereas last year it was a little different. People thought of Bagwell and Biggio and an offensive juggernaut."

St. Louis, too, has undergone more than just subtle tweaks. A year ago, Scott Rolen was solidifying his reputation as "probably one of the best third basemen ever to play the game," La Russa said, coming off a career year in which he hit .314 with 34 homers and 124 RBI. This year, he went down in July with a shoulder injury, hasn't played since and has been replaced by a 29-year-old career utility player named Abraham Nunez.

The Cardinals' middle infielders a year ago were Tony Womack, recently ousted from the playoffs with the New York Yankees, and Edgar Renteria, recently ousted from the playoffs with the Boston Red Sox. They were replaced by second baseman Mark Grudzielanek and shortstop David Eckstein, respectively, a nondescript pair that has fit in quite nicely despite the pressure of being expected to immediately help the team return to the World Series.

"We know we're here for a reason," Grudzielanek said, "and they believe in us."

Nowhere, though, will the changes from a year ago be more apparent than on the mound. Carpenter is coming off a season worthy of the Cy Young Award. He won his first start of the postseason, beating the San Diego Padres in the division series. And he remembers watching last year's drama from the side. "Frustrating," he called it.

Pettitte will be making his 32nd postseason start, and he is 6-1 in championship series play. He reiterated that, after the 2003 season, he signed with his hometown Astros not to be hurt and sit out the playoffs, like a year ago, but to take the ball in such situations.

"Last year, they did it without me," Pettitte said. "Hopefully, this year I can help us get past this round."

Carpenter, too, could say the same thing. The mixes, the talent levels, the experiences might be different. But would anyone be surprised if Cardinals-Astros '05 mirrored the drama of Cardinals-Astros '04? Not at all.

"I think the matchups all around the field are close," La Russa said. "I think it's a pick-'em thing. It makes for classic baseball."

The Cardinals' Chris Carpenter missed last year's NLCS against the Astros because of injury. This year, he is a leading contender for the Cy Young Award. Roger Clemens, left, and Andy Pettitte make up the Astros' big three with Roy Oswalt. Pettitte missed the postseason last year.