The Sox lead MLB in runs and OPS, but they have just one really good bat, Ortiz's, who opposing managers don't mind walking intentionally or even semi-intentionally.
And they don't have even one really good righty bat to take advantage of the green monster and generally have problems hitting against lefty starters. In fact, there have been several threads saying the Sox badly need one good righty bat. Pedroia, Iglesias, and Napoli are actually pretty good, but the first two don't hit many dingers, and Napoli's homer output is tapering off.
So why all those runs scored and the high OPS? My version is it's combination of depth--not just in the everyday lineup, but in guys who go in and out of the lineup and up and down from Pawtucket--and the success of the lefty bats in using the green monster. And some of the lefty success, I contend, is the result of AGon setting the example while he was here, which Ortiz followed and has had great success doing so, and which other guys like Carp, Drew, Ellsbury, Victorino, and Nava (but not Salty) are now also doing. The thing about the green monster is it just might be a better offensive weapon for a lefty hitter than a righty one because it can yield a lot of doubles and singles on balls that would otherwise be caught. In other words, the Sox basically have a lefty-heavy lineup which does not seem to miss that big righty bat because they are all, except for Salty, hitting to all fields effectively.
As for the depth thing, I consider it signficant that so many guys in the lineup, including the usual #9 hitter Iglesias, can start a rally or drive in a key run. On top of that, utility guys like Carp and Gomes have made contributions. Plus Middlebrooks, the guy currently playing workup in Pawtucket, might yet turn into that big righty bat he seemed to be last year. Or maybe Bogaerts, who just moved up to AAA. If an outfielder goes on the DL, Bradley, another lefty bat, will no doubt return. Napoli's dingers are less frequent, but he is still driving runs in, especially after IBB's to Ortiz. Plus, if a righty starter is especially tough, Farrell who put Nava or Carp at 1B and the other one in the outfield.
And don't forget the chemistry thing. The infamous Bailey had 8 saves in 12 save opportunities. But the Sox only lost one of those four games in which Bailey blew the save. They actually won three of them because these guys are very good at picking each other up.
Recently against the Rays Bailey blew a two run lead in the 10th, but the team came off the field pumped up and enthusiastic because the situation had been much worst than those two runs scored. The Rays actually had the bases loaded with nobody out and the score already tied in the bottom of the 10th with Longoria coming to the plate. With the infield in, Longoria hit a one hopper to Middlebrooks, who threw home to Salty, who then made a great throw to 1B to get a double play. The next batter drag bunted to Pedroia who charged in and threw him out at 1B. The Sox scored 2 in the 14th to win it.