They own the second-best record in the American League and a comfortable -- if not exactly impenetrable -- lead over the second-place New York Yankees.
They lead the league in most offensive categories, and despite some breakdowns and rough patches over the course of the season, are currently getting their best stretch of starting pitching as the regular season winds down.
They seem a virtual certainty to return to the postseason for the third straight October. And yet, the Red Sox can't help but ask themselves: What if?
What if Keith Foulke had been healthier, and thus, as productive as he was a year ago, when he was a major factor in the club's winning its first championship in 86 years?
As it is, Foulke missed almost two months following arthroscopic knee surgery, and the first three months were beyond disappointing. Through July 4, Foulke had blown four saves. But that's not the half of it. He also gave up eight homers in the first half of the season, the same number he yielded all of last season. And while Foulke allowed only four leads to get away, even the saves he recorded were, to put it politely, rocky. His ERA in save situations was in double digits, and seemingly routine chances routinely turned into seat-squirmers.
It may be inaccurate to suggest no lead was safe, but it's not a stretch to say that Foulke's entry into the game brought with it a sense of trepidation for the Sox.
What if Foulke had been better?
Or, what if the Sox had Mariano Rivera in the bullpen? What if the Sox could hand over late-inning leads to, arguably, the best closer of the modern era, the most successful postseason closer in history?
What if they had Rivera rather than a damaged Foulke for the first three months? What if they didn't have to interrupt Curt Schilling's rehab to reassign him to the bullpen? What if they could have kept Mike Timlin in the set-up role, where is he is significantly more effective and comfortable?
What if, indeed.
It's a safe bet that if the Sox had Rivera:
* They wouldn't have been outscored by 13 runs in the ninth inning this season (Opponents 69, Red Sox 56).
* The team wouldn't sport the highest bullpen ERA in the American League and the second-worst in all of baseball, behind only the Arizona Diamondbacks.
* Boston wouldn't have accumulated 15 blown saves since the start of the season, including one by Foulke in the second game of the season.
As it is, the Sox have utilized three closers to date, and with just over three weeks remaining in the season, Foulke still hasn't been able to reclaim his role.
When Foulke went on the DL July 6, the Sox muddled through the rest of the first half, then tried Schilling, who hadn't pitched in relief on a regular basis for a dozen years.
In time, Schilling brought some stability to the ninth inning. Like Foulke, he made some leads shrink, but let only two get away.
By the end of August, however, Schilling told Red Sox management that if they wanted him to start in October, he would have to return to the rotation soon, to build up his arm strength and get reacquainted with the rigors of starting.
While the Sox mused about the option of trying rookie Jonathan Papelbon, or recent draftee Craig Hansen, in the role, they settled on Timlin, who, by his own admission, has always been more effective in the seventh and eighth innings than the ninth.
In the last two weeks, Timlin has warmed to the task, converting all four of his chances since Schilling returned to the rotation. But while Timlin has bought Foulke additional time, he isn't the long-term answer. He's not even the answer for October.
For that, the Sox must hope that Foulke can improve his command and velocity -- both were lacking in the first half of the season, due at least in part to his unstable knee -- and at least share some of the ninth-inning load. Foulke has pitched just three times since coming off the DL on Sept. 1, and each time, he entered the game with the Sox behind, an indication of how much more he must progress before the team again can entrust him with the lead.
Rivera, of course, needs no help, or introduction. Since taking over for John Wetteland as the Yankees' full-time closer to begin the 1997 season, Rivera, along with Derek Jeter, has been the one constant for the Yankees in the Joe Torre Era.
Pressure not only fails to faze him, it seems to embolden him. On the rare instances in which he's failed -- Game 7 of the 2001 World Series, the 2004 ALCS against the Red Sox -- he's successfully put the disappointment behind him.
Two years ago, and again earlier this season, there were whispers that Rivera had dipped, that his cut fastball wasn't quite as lethal. He found himself being booed in April when the Sox themselves got to him and stole a game at Yankee Stadium. Red Sox fans mockingly cheered him at the Fenway Park home opener and flag-raising, and Rivera had the grace and humor to smile and acknowledge the ovation.
But that was April. This is September. And once again, Rivera is the best in the business at what he does -- slamming the door shut in the late innings, crushing any hope opponents have of a comeback.
Rivera is 6-4 with 1.49 ERA and has converted 36 of 40 save opportunities. Take away two rough outings against the Sox in the first month, and he's blown only two saves since. Hitters are batting a paltry .175 against him.
In time, Foulke could return to form and the Red Sox may yet successfully defend their title.
But it sure would be a lot easier with Rivera in the bullpen. Just ask the Yankees.
Sean McAdam of The Providence (R.I.) Journal covers baseball for ESPN.com.