The Red Sox stood on the sidelines and watched as the Braves and Phillies took part in the B.J. Upton battle, an NL East competition that resulted in the 28-year-old receiving a five-year, $75.25 million deal from Atlanta.

According to an industry source, the Red Sox never really engaged in the Upton sweepstakes and they never made an offer. The fact that the Red Sox sat on the sidelines for one of the top free agents of the offseason (and that they have no plans to engage the other premium center fielder on the market, Michael Bourn) is telling in its own way, on a few fronts.

First, if the Sox had envisioned a trade of Jacoby Ellsbury this winter as likely or even just a legitimate possibility, then they might have been expected to at least dip their toe in the water with Upton. After all, Upton is 28 years old, has averaged 19 homers and 36 steals over six full-time seasons with a line of .255/.338/.430/.768 during that time.

The opportunity to get a player with Upton’s combination of power, speed and solid defense at a premium defensive position (center field) in his age 28-32 seasons -- smack in the middle of his prime -- is a rare one in free agency, even with the caveat that his OBPs have inexplicably fallen off a cliff, going from .386 in 2007 to .298 in 2012. 

But Ellsbury's trade value is likely at an all-time low coming off a 2012 season that was undone by injury and then poor performance (.271/.313/.370/.682). He has just one year left before reaching free agency, and as a third-time arbitration eligible player, his salary will be higher than ever.

Given all those factors, the team seems inclined to keep him as its everyday center fielder in 2013 and hope for a bounce back that either will offer the Sox a player who can help turn one of the Sox' foremost competitive disadvantages in 2012 into a considerable competitive advantage, thus giving the team a shot to contend, or that if the team falls out of the race, will boost his trade value during the season beyond where it resides now.

(On the subject of the impact Ellsbury can make to a potential Sox contender, it’s startling to consider this: Red Sox center fielders combined, according to the witchcraft on Fangraphs.com, to produce 0.4 wins above replacement last year -- the second-worst mark in all of Major League Baseball. In 2011, when Ellsbury was the best position player in the American League, the team enjoyed a 9.4 WAR from its center fielders.

In other words, by himself, the 2011 version of Ellsbury could have improved the Sox to a team with a record that was nearly .500. Even if he gets halfway to that standard in 2013, improving the Sox by four or five wins, that’s a pretty significant boost from one position on the field.)

Secondly, the fact that the Sox haven't been aggressive in the market for premium center fielders further underscores the team's future comfort level with Jackie Bradley Jr., and with good reason. The 22-year-old hit .315/.430/.482/.912 with 42 doubles and 55 extra-base hits in 128 games in 2012, his first full pro season. While his numbers dipped a bit after a mid-year promotion to Double-A (.271/.373/.437/.809 in Portland), he profiles as an elite defensive center fielder with the on-base skills of a prototypical leadoff hitter.

Bradley is still not major league ready, though based on the developmental progressions of top position players such as Ellsbury and Dustin Pedroia through the system (the recent Red Sox position prospects whose college pedigrees most closely resembled that of Bradley), it wouldn't be a surprise to see Bradley in the big leagues in 2013 with an everyday job in 2014.

If the team had been hedging its bets on Bradley, then it might have been expected, again, to explore the market for Upton and Bourn. But the team didn’t do so, given its comfort with the idea of its short- and long-term options at the position.

Finally, the Upton contract represents the first free-agent deal for a premium center fielder in a number of years. It’s almost startling to take stock of how limited the recent pools of free-agent center fielders have been. Here’s a complete list of multi-year deals signed by free-agent center fielders in the four offseasons that preceded this one:

2011-12: Coco Crisp, A’s, 2 years, $14 million
2010-11: None
2009-10: Mike Cameron, Red Sox, 2 years, $15.5 million
2009-10: Marlon Byrd, Cubs, 3 years, $15 million
2008-09: Willy Taveras, Reds, 2 years, $6.25 million

You have to go back to the winter of 2007-08, when Torii Hunter signed a five-year, $90 million deal with the Angels, Aaron Rowand signed a five-year, $60 million deal with the Giants, Andruw Jones reached a two-year, $36.2 million deal with the Dodgers, to find players the last deal for a center fielder of at least four or more years and at least $10 million a year.

That scarcity is a reminder that, in case you were wondering, Ellsbury is in line for a big, big payday when he reaches free agency, so long as he can stay healthy in 2013 and return his production to at least his career norms. Upton’s deal shows that even without a consistent track record of excellence (he’s never been an All-Star, and only once has he had an OPS over .800), teams are willing to make expensive, long-term commitments to players based on their tools and upside. Given the extraordinary upside shown by Ellsbury in 2011, it’s hard not to see him go zooming past Upton’s price tag so long as he can remain healthy in 2013 -- a season that he seems almost certain to open with the team that drafted him in 2005.