Champagne celebrations in September have become commonplace enough for the Philadelphia Phillies over the last half-decade that a certain neighborly ritual has come to govern them: After bounding off the field, the Phillies gather in their clubhouse around the tubs of iced-down bubbly and call for their newest member to step forward and pop the first cork.

And so it was late Saturday night that Hunter Pence, the right fielder who became a Phillie on July 29, moved to the center of the Phillies’ clubhouse — much as Roy Halladay, a first-time Phillie in 2010, had a year earlier — and popped the cork off the first bottle, at which time he was immediately set upon by his champagne-wielding teammates, an ambush that left Pence drenched and beaming.

“They were waiting for me,” Pence said, “and they blew me up.”

Fresh off the clinching of their fifth consecutive National League East division title, and as they look ahead to Game 1 of their NL first-round playoff series at Citizens Bank Park on Oct. 1, the Phillies could scarcely have drawn up a better ending to their regular season. Despite a second consecutive loss to the St. Louis Cardinals on Monday night — on a night their ballpark hosted its 200th consecutive regular season sellout — the Phillies have 98 wins, eight more than anyone else in the NL.

The Phillies could reach the 100-win mark during a four-game series against the Washington Nationals that begins with a doubleheader Tuesday, and with a little more than a week left in the season, should obliterate the franchise record of 101, set in 1976 and equaled the following year.

“I think [the win total] is an indication of how consistent we were,” said Phillies Manager Charlie Manuel. “This year we were the most consistent we’ve been.”

Much of the the team’s success has been built upon their historic collection of starting pitching — Halladay, Cliff Lee and Cole Hamels ranked second, third and fifth in the NL in ERA (minimum 170 innings) entering Monday. But within the Phillies’ clubhouse, the trade for Pence, who was acquired from the Houston Astros for four prospects, is viewed as the season’s turning point.

Before July 29, the Phillies were a very good team that seemed headed for the postseason, and had as good a chance as any to win it all.

After July 29, they became a regular-season monster that — some two months later, and with a 33-15 record since the Pence trade — should enter October as an overwhelming favorite to advance to the World Series for the third time in four years.

Pence, 28, has given the Phillies what they lacked following Jayson Werth’s defection to the Nationals in December — a right-handed power threat to hit fifth in their lineup behind perennial all-stars Chase Utley and Ryan Howard. Pence’s batting line since his arrival in Philadelphia (.315 batting average/.386 on-base/.545 slugging) is eerily similar to what Werth produced in 2010 (.296/.388/.532) in the same role.

But unlike Werth, whose introspective, mercurial nature belied an intense competitiveness, Pence, rawboned and indefatigable, has injected the Phillies’ with a dose of youthful energy — no small matter for a team on which five of the remaining seven position players are 32 or older, and that is currently in the midst of a grueling, season-ending stretch of 33 games over a 31-day span.

“Him and Jayson are two completely different personalities,” Manuel said of Pence. “This guy is high-strung. He’s brought a freshness, a different look. It’s all energy. But not only that — he’s a great hitter. He’s a .300 hitter, with power.”

Pence has played in every inning of every game since his arrival in Philadelphia, and just in case Manuel had any ideas of benching him down the stretch to keep him fresh for the postseason, he dispelled his manager of that notion on Monday.

“He told me, ‘I’m not trying to look ahead or anything, but Washington has got three lefties [scheduled to pitch against the Phillies], and I want to play against all of them,’” Manuel said. “I’m telling you, this kid comes to play.”

Pence also helps obscure what is the Phillies’ biggest flaw, the one that keeps their fans up at night: an offense that, even now, suffers through long bouts of impotence. Monday night’s 4-3 loss, in fact, marked the 10th time in their last 11 games the Phillies have scored three or fewer runs. The middle of their lineup, once the bane of opposing pitchers, now is pocked with holes. Howard’s batting average (.249) and OPS (.833) are the lowest of his career, while Utley is hitting just .230 with a .637 OPS since Aug. 1.

Numbers such as those, coupled with the ages of the Phillies’ core players, underscore how crucial Pence is to the franchise’s future — not only for the 2011 postseason, but well beyond. Although Pence is under team control through the 2013 season, one Phillies executive believes it will be a priority this offseason to lock him into a lengthy, multi-year contract.

“Seeing what he has done for us [since his arrival], the energy and the ability, has been a revelation,” the executive said. “This guy is the future.”