BOSTON — Jacoby Ellsbury, the leadoff man on the Boston Red Sox’ last two World Series champions, began the team’s first rally Wednesday night with a single. Mike Napoli, the thick-bearded first baseman, singled in a run an inning later. Stephen Drew, the sure-handed shortstop, broke out of an autumn-long funk with a home run, and the Red Sox overwhelmed the St. Louis Cardinals in Game 6, setting off a Fenway Park celebration unlike any other.

In the haze from the fireworks on the field, players and coaches alike theorized about what it took to turn around a team that had finished in last place a year earlier. David Ortiz, the World Series MVP and October legend, credited John Farrell, the first-year manager. Farrell, in turn, credited General Manager Ben Cherington, who provided him with driven, like-minded players, many on reasonable, short-term contracts. It was a swift reversal, whoever gets the commendation.

But as much as the Red Sox players who embraced each other — and the city of Boston, battered by April’s marathon bombings — will be remembered in New England, the way the team was built could mean it needs to be rebuilt this winter. Ortiz, proven ace Jon Lester and surprise closer Koji Uehara are under contract through next year (Lester by virtue of an option in his contract that the team will all but certainly pick up).

Yet other key parts will have to be re-signed — or replaced.

“This is one of the best organizations, since I’ve been here,” said Ortiz, the only link to the 2004 World Series champion still in place this year. “You have those funky years that you put a really good team together and you don’t make it to the playoffs, and you have those other years that you let a big player go, and all of a sudden you’re in the playoffs. This organization, as long as I’ve been here, has been a box full of surprises.”

What will the surprises be this offseason?

The Red Sox, from the front office to the coaching staff to the clubhouse, said the camaraderie created contributed to their success, though that’s an impossible quality to quantify. But they also know that playing in Boston is not for everyone, and they need to find players who excel, not shrink, under the microscope.

“I think, in the eyes of some, Boston might present some specific challenges that might be intimidating for certain players,” Farrell said. “But I would hope what they’re witnessing would certainly become a place of destination for a number of guys that might have a choice.”

Internally, the Red Sox have discussions about what players might hold up well in the atmosphere.

“That’s tough to gauge,” said Zack Scott, the team’s director of baseball operations and one of Cherington’s top lieutenants. “We’ve brought in star players that haven’t thrived in this environment, this fishbowl environment.

“We have a good feel for the pressure that’s involved with playing for the Red Sox. It’s a big city, but it’s a small-town mentality. Pro sports are just so big here, so whether we think a guy can handle it is definitely a factor.”