FORT MYERS, Fla. – Yes, the Red Sox reinforced their lineup with the acquisitions of Adrian Gonzalez and Carl Crawford as well as the returns to health of Dustin Pedroia and Kevin Youkilis. And yes, the team’s bullpen should be upgraded thanks to the signings of Bobby Jenks and Dan Wheeler.

Yet while those are the most obvious areas of reinforcement that have fueled the talk of a 100-win team – inside and outside of the clubhouse – they may not even represent the most significant area of improvement for the 2011 Sox.

A year ago, the team’s outfield defense was expected to be tremendous. The signing of Mike Cameron was predicated upon the Sox’ commitment to upgrade a defense that had been an area of weakness in 2009. The team envisioned having a former Gold Glover in Cameron patrolling center, Jacoby Ellsbury covering every square inch of left field and having J.D. Drew deliver his typically outstanding defense in right.

It didn’t happen that way. Not even remotely.

Drew ended up getting the lion’s share of time in right, starting 127 games. But the unexpected twists of the season featured Darnell McDonald, primarily a corner outfielder in his career, taking more starts (50) than any other Sox in center. And left field was manned by Daniel Nava (44 starts), Bill Hall (42) and Jeremy Hermida (41).

The Sox used a staggering 44 outfield combinations, many with players who were average or a tick below at the position. While Drew delivered the expected better-than-average work in right, according to the team’s defensive metrics, the Sox fell short of that standard at the other two positions.

The result was, overall, an outfield that was slightly below average. As such, GM Theo Epstein saw the outfield defense as an area in which he could better the team for the coming year.

“That’s one of the ways we can improve,” said Epstein. “We had so many different outfielders and outfield combinations that, as a whole, it wasn’t very good because of the injuries.”

While there are readily available statistics to determine how good an individual’s outfield defense is, it can be trickier to measure precisely how good or bad a team’s total outfield defense is. One way of doing so is to look at how often outfield fly balls (not including homers or line drives) end up being caught and how often they fall for hits.

WEEI.com’s Gary Marbry crunched the numbers from the last four years to see how the Sox stacked up in comparison to the other 29 clubs in regards to catching fly balls.

In 2010, outfield fly balls resulted in a .207 batting average against the Sox. That mark ranked second to last in the majors. By way of comparison, the best team in the majors at converting outfield flies into outs in 2010 was the Reds, who allowed a .131 average of fly balls.

Of course, the measure is imperfect, because park effects can be extreme. Fenway, in fact, may be one of the most difficult parks in which to evaluate a team’s outfield defense because of the dramatic impact that the Green Monster has on lazy fly balls – would-be outs regularly clang off the left-field wall for hits.

So, Marbry removed also ran the numbers while removing all outfield fly balls at Fenway. In that scenario, outfield fly balls fell safely for hits to the tune of a .163 average, a mark that ranked 14th in the majors – roughly middle of the pack.

But that number was a far cry from the tremendous outfield defense that characterized the 2007 World Series-winning Sox, who permitted a .124 average on non-Fenway outfield flies, tops in the majors. Not coincidentally, that Sox team allowed the fewest runs of any Sox squad in decades.

The 2007 Sox are not alone in having benefited from airtight outfield defense. In 2008, the Rays topped the majors in converting outfield flies into outs; they reached the World Series. In 2009, the Mariners paced the majors; though they missed the playoffs, they were surprise contenders that year. In 2010, the Reds had the best rate of turning fly balls into outs; they reached the playoffs for the first time in 20 years.

Such performances offer a reminder. There is ample room for the Sox to improve in that particular aspect of their club, something that informed the team’s winter strategy. 

“We lost Jacoby, who was one of our best defenders. Cameron was never himself,” said Epstein. “J.D. played well. The guys who came up did a good job, but it took them a while to get adjusted to the big leagues, the ballpark, things like that. It certainly wasn’t the strength last year that it should be this year.”

This year, the Sox are bringing Drew back to right, where he has offered a steady diet of above-average defense during his Boston tenure. Ellsbury is expected to make a healthy return to center, upgrading the team significantly from the damaged Cameron of 2010 as well as the shuffle of players like Bill Hall, Jonathan Van Every, Darnell McDonald and others.

And newcomer Carl Crawford is expected to provide not just good but exceptional defense in left. Nearly every member of the Red Sox lineup has a story about getting robbed by Crawford; clearly, they are relieved that the glove is now on the other arm.

"Now you can score on my [expletive] instead of catching my [expletive]," David Ortiz bellowed to his new teammate upon his arrival on Thursday morning.

Crawford was finally awarded a Gold Glove in 2010, making him the first AL left fielder in 30 years to be so honored, and his highlight-reel defense in the gaps has placed him (by virtually every advanced defensive measure) among the top handful of outfield gloves in the game for several seasons.

“He’s exciting. He’s a dynamic player. In my opinion, he’s one of the best players in the game -- not just because of what he does offensively, but defensively,” explained Sox reliever Dan Wheeler, who spent the last four years with Crawford in Tampa Bay. “As a pitcher, that’s the guy you want behind you. There’s no question. There’s just so many plays he can make out there -- take a single away on a bloop hit because he’s so fast, take a double away because he’s diving full-out into the gap and makes the catch. The speed he has, the jumps he gets on balls, it’s just amazing.”

The Sox expect Crawford to impact his outfield neighbors. In contrast to the years when Sox outfielders were responsible for ground left uncovered by Manny Ramirez, because Crawford can cover such a large plot of lawn in left and left-center, he can reposition his outfield teammates.

“It makes my job easier. It makes the right fielder’s job easier,” said Ellsbury. “There’ll be a lot of balls caught in the left-center gap. I can play straight up most of the time. It’ll be nice, playing with someone that has that much speed.”

That could be particularly important for some members of the Sox staff. Daisuke Matsuzaka, for instance, is one of the most extreme flyball pitchers in the majors. Tim Wakefield and Jonathan Papelbon also tend to get fly balls at high rates.

While everyone on the Sox pitching staff would benefit from improved outfield defense, those are a few examples of pitchers who may experience the greatest gains from a potential Crawford effect. 

“The idea would be that there’s not a lot of balls that hit the ground,” said Sox manager Terry Francona. “I talked last year, like when we’d go into Tampa or go into Seattle, you’d hit a ball, think you had a double, make a right turn and come back to the dugout. That speed should play in the outfield. That’s what we’re hoping for.”

Of course, there are no guarantees. After all, a year ago, the Sox were being touted as having a similarly impressive alignment. Then, injuries ravaged their outfield.

Even so, if the Sox benefit from Crawford and a returning Ellsbury as much as they anticipate, one of the least discussed aspects of upgrade for the 2011 club may turn out to be one of the most meaningful.