BOSTON — It’s been said that you can’t win a pennant or a division, for that matter, in the first two months of the season, but the Red Sox may be in the process of disproving that theory.

Even after yesterday’s split-decision with the Atlanta Braves — a 13-3 thumping for the Sox in the day portion, followed by an even more lopsided 14-0 Braves’ win in the nightcap — the Sox stood a full 9 1/2 games in front of the Baltimore Orioles and 10 ½ in front of the spiraling New York Yankees.

Put in perspective, that represented the biggest lead the Sox have ever enjoyed this early in the season. Only the 2001 Seattle Mariners, who won a record 116 games, could boast of a bigger lead after 41 games. Those Mariners, at 31-10, led the Oakland A’s by 12 games.

Of course, the Red Sox aren’t interested in history or the size of their May margin.

“We’re doing a good job at playing them one game at a time,” said first-game hero Mike Lowell, who had four hits, including a grand slam. “We’re really concentrating on the game at hand. We’re doing a good job of being in the present moment and taking care of what we have to.”

Indeed, the Sox have been a measure of consistency. Not since a two-game set at home with Toronto April 23-24 have the Sox lost a series. Since the start of the season, the Sox have lost just two series. In their last 16 games, they’re 13-3. Entering yesterday, they had exactly the same record at home and on the road.

Meanwhile, the Yankees continue their free fall. Yesterday, they lost yet another starting pitcher, Darrell Rasner, to injury and are assured of losing their interleague series with the Mets.

For the second time in the last month, the Red Sox will arrive in New York tomorrow night with Joe Torre’s job security uncertain. Losing back-to-back series to their two chief rivals to plummet deeper out of contention even before Roger Clemens can arrive on his white steed will not go over well with Boss Steinbrenner.

If the Yankees can’t salvage their season, is there another viable contender in the division? Six weeks ago, Toronto would have been the obvious choice, but after losing closer B.J. Ryan for the season and going without ace Roy Halladay for the next five weeks, the Jays seem doomed for 2007.

Baltimore? The Orioles have plenty of talented arms, but the rest of the roster seems a poor fit of mismatched, underperforming sluggers. Tampa Bay? In another three years, maybe. Not now.

All of which suggests that the Red Sox comfortable lead hasn’t entirely been self-generated. Call it a confluence of events: the Sox playing well and remaining (mostly) healthy while the rest of the division sputters. For the first time in a long while, the A.L. East can’t lay claim to being the best division in the league.

Besides, there’s better than four months of baseball left, plenty of time for injuries to interrupt and slumps to hurdle. It’s worth noting that the 2002 Red Sox began the season 40-12 and not only didn’t hold on to win the division, but didn’t qualify for the postseason.

While some continue to point out that the Sox are in first without much in way of contributions from Manny Ramirez (.252), that’s balanced by the fact that its unlikely that neither Lowell (35 RBI in 39 games) nor Kevin Youkilis (.333) will continue to produce at their current pace.

In all likelihood, pitching will be a far greater determinant. How well the Sox weather the absence of Josh Beckett and Beckett’s subsequent durability upon his return will go a long way toward determining the Sox’ long-term viability.

If Beckett returns and makes another 25 or so starts, the Red Sox’ rotation remains as deep and as formidable as any in either league. If his finger becomes a season-long concern or another of the team’s Big Four suffers a significant injury, the Sox’ blistering start may not be enough of a cushion in the event of a second-half drop-off.

Almost exactly one-quarter of the way through the season, however, you have to like their chances.

smcadam@projo.com