By Tommy Rancel

The Boston Red Sox made a conscious effort this off-season to improve the team in terms of run prevention. The highlights of the Red Sox off-season include the signings of respected defenders Mike Cameron in center field and Adrian Beltre at third base.

While Epstein is on record as saying he doesn’t agree with some publicly found defensive metrics (presumably Ultimate Zone Rating aka UZR, which rated Jacoby Ellsbury as one of the league’s worst center fielders last year), his actions suggest otherwise. Even before Jason Bay signed with the Mets, leaving a void in the Boston outfield, Epstein saw the need to sign an able defender like Cameron as an upgrade.

Despite Epstein’s support for Ellsbury as a center fielder, and the fact that Cameron is 10 years older than Ellsbury, it is Cameron who is patrolling center field for Boston this season.

Looking at UZR, Cameron is a perennial favorite of the metric. Even at his advanced age of 37, he is rated well above average (10.0 UZR in 2009). Ellsbury on the other hand has bounced around the spectrum, rating well above average in 2008 (+16.5) to well below in 2009 (-18.6).

The Ellsbury/Cameron moves highlight the outfield changes, but Beltre at third base is another gift to Boston’s pitching staff. Regardless of your fielding metric of choice, Beltre is a consensus top defender at the hot corner. His 14.3 UZR ranked fourth-best among major league third basemen, and he was runner-up at the position to Ryan Zimmerman in the 2009 Fielding Bible Awards. His plus/minus, a defensive statistic created by John Dewan, is also second to Zimmerman at third base over the past three seasons.

Looking at the Red Sox third basemen in 2009, Beltre will be a welcome addition to the left side of the infield – Mike Lowell (-10.4 UZR in 895 innings) and Kevin Youkilis (-1.6 UZR in 494.1 innings) were both below-average defenders in 2009. The Red Sox will also welcome Marco Scutaro to the left side. In his first full season at the position in 2009, Scutaro rated just above average at shortstop.

It is easy to pick out a few positions and point out the flaws, but the Red Sox as a team posted a UZR of -16.3 last year. This led to a highest-in-MLB batting average on balls in play (BABIP) of .320. For comparison’s sake, the Seattle Mariners led the league in team UZR with 85.5 runs above average. Not surprisingly, they also had the lowest team BABIP in the majors at .280. The design of Fenway Park leads to some quirky BABIP in itself, but the Red Sox maintained a .297 team BABIP in 2008, and .292 while winning the World Series in 2007.

The Red Sox staff as a unit should benefit greatly from the improved defense, but Jon Lester especially. Fans of other AL East teams might want to close their eyes, but with a .323 BABIP in 2009, Lester was still good enough to maintain a 3.41 ERA. As a pitcher who yields comparable numbers of groundballs and flyballs, Lester should benefit from all the additions, and could see his BABIP fall this season. This could mean an improvement in his numbers, across the board.

Beyond Lester, young righty Clay Buchholz and his career groundball percentage of nearly 49.9% should greatly benefit from the above-average infield defense of Beltre, Scutaro, Youkilis, and Dustin Pedroia.

Feel confident in Boston pitchers not only for their individual abilities, but also because of the imported vacuum cleaners brought in to upgrade the defense. That those pitchers figure to benefit from solid run support won’t hurt either.

For more on the Boston Red Sox pitching staff, check out Bloomberg Sports’ fantasy kits.