The driving force behind Boston's sterling first half has been its potent offense, which leads the major leagues in runs, doubles, and OPS.
C Jarrod Saltalamacchia
After back-to-back middling seasons as Boston's backstop/Jason Varitek's replacement backstop. Salty seems to have settled in and looks more comfortable with the pitching staff. He's improved with the stick as well, even if he isn't hitting for as much power as he did during 2011-'12, when he smashed 41 home runs with a .224 ISO. It's troubling that he's fanned in more than one third of his plate appearances so far and has benefited from a fluky .387 BABiP. He's compensated by already establishing a new career high in doubles and boosting on-base percentage nearly 50 points thanks to a much improved walk rate. After posting a .288 OBP in consecutive seasons he's been more selective at the plate, a relief for those who feared he was nothing more than a J.P. Arencibia type.
1B Mike Napoli
The returns on him have been good so far, even though he's nowhere near the player Adrian Gonzalez was in his brief stint with the Sox. The degenerative hip condition that scared Boston into restructuring his contract hasn't been an issue for Napoli, who's been in the lineup almost everyday and provided his usual power and on-base ability. His 2011 aberration notwithstanding, Napoli is never going to be Manny Ramirez, but he's formed a strong 1-2 punch with David Ortiz in the heart of Boston's order. He's had his share of ups and downs, with a nasty two month long slump of .242/.343/.331 nestled between his red-hot first month and monster July. Like Saltalamacchia, he's likely to see some regression if and when his .383 BABiP comes back to Earth, especially since Napoli is walking less and striking out more often than ever before. Perhaps the most surprising thing about his season so far is that he's hit better on the road (.832 OPS) than he has at Fenway (.819). He also has a healthy RBI total despite not performing particularly well with men on base, so if that changes he'll likely make a run at his first 100 RBI season.
2B Dustin Pedroia
Pedroia's bounced back nicely from a "down" 2012 and just received a contract extension that will keep the former MVP in Beantown through 2021. More on that to come.
3B Jose Iglesias
Will Middlebrooks, the Opening Day third baseman and heir apparent to Kevin Youkilis, was such a black hole on offense (63 OPS+) that he needed a demotion to Pawtucket. That allowed Iglesias, a shortstop by trade, to man the hot corner while Drew plays short. The 23 year-old Iglesias has become the early frontrunner to win American League Rookie of the Year thanks to his sensational defense and unsustainable batting average. His .343 mark looks a lot less impressive given that more than 81 percent of his hits are singles and is guaranteed to fall along with his .393 BABiP. In fact, his inevitable regression to the mean is already well underway. Over the past month he's been the all-glove no-stick ballplayer he's always been, batting just .227 with one extra base hit--a double. For all his good luck and infield singles, he's still not a capable major league hitter and probably never will be. Xander Bogaerts is the team's future at shortstop.
SS Stephen Drew
J.D. Drew's little brother has been a disappointment so far, bearing little resemblance to the All-Star caliber player he was with Arizona. Showed signs of life with a solid June, only to miss three weeks with hamstring tightness that derailed his momentum. He's always been more of a second half player, with a career OPS 54 points better after the All-Star Break than before it, so hopefully he'll find his June swing and be fine going forward.
LF Daniel Nava
The miracle worker's evolved from a feel good story into a legitimate All-Star candidate. He carried the team on his back during the season's first three weeks, helping Boston jump out to a fast start. Since then he's continued to drive in runs while maintaining a strong OBP. Suffice it to say, Nava's provided much more than anyone could've possibly hoped for at the beginning of the year.
CF Jacoby Ellsbury
The major league stolen base leader has recovered from a sluggish start, boosting his batting average above .300 on the season. He's posting the best walk rate of his career which, combined with his excellent batting average, has him primed to score 100 runs for just the second time in his career. His three month drought between longballs proves that his bizarre power surge was indeed an aberration, but then again it's hard to go yard when you're hitting nearly two balls on the ground for every one you lift into the air. The speedster's recouped some of that lost value by being more aggressive and efficient on the basepaths, swiping bags at a 92.5 percent clip. More than anything, health has been the key to his success, as he's already played more games in 2013 than he did in 2010 and 2012 combined.
RF Shane Victorino
The 32 year-old has had his issues staying on the field, missing 34 games already. But when he's played he's been more than capable. In addition to supplying plenty of his plus defense and baserunning, he's been better at the plate than he was last year thanks to better results batting from the left side. That's allowed Farrell to bat him out of the two hole in 60 of his 70 games, allowing Victorino to be a table-setter instead of sliding him down in the order (what happened to Carl Crawford).
DH David Ortiz
Despite opening the season on the DL, Ortiz picked up where he left off in 2012 by getting off to a torrid start. Big Papi has far and away been the team's best hitter all year, leading the club in most offensive categories and anchoring the heart of Boston's order.
Mike Carp has been spectacular and Jonny Gomes is coming around. Otherwise, there isn't really too much to say.