C.J. Wilson and Jonathan Papelbon were born within a week of each other in November 1980. Both broke into the majors in the middle of the 2005 season, a year in which, after dabbling in the rotation, they moved into the bullpen. Both took up residency in the ‘pen for several years thereafter. And for the first time in their careers, both reached free agency this year.

Among relievers to reach free agency, Papelbon’s credentials built over his first six full seasons in the majors were virtually unmatched. He was paid like it when the Phillies gave him a record-setting $50 million, four-year deal -- the most guaranteed money ever given to a reliever.

Wilson had two excellent seasons as a starter on his resume after a solid but fairly undistinguished career as a reliever. Through four-plus seasons in the majors, he enjoyed sporadic opportunities to close, but mostly was viewed as a reliever whose command inconsistency limited his role.

The Rangers moved him to the rotation in 2010 with terrific success. In a pool of all major league starters, he has performed at the level of one of the top 20 or 25 in the game. Certainly, his stature as a starter lags far behind Papelbon’s as a closer, but the left-hander represented a solid front-half of the rotation starter when he reached free agency this winter.

Yet it was Wilson who made a splash with his arrival at the end of the winter meetings in Dallas earlier this month, where he agreed to a five-year, $77.5 million deal with the Angels. He received an extra year over what the Phillies offered Papelbon, and his guaranteed payout exceeds Papelbon’s by more than 50 percent.

Wilson’s deal offered a dramatic illustration of the degree to which baseball values starters over relievers. Wilson will never take a place in a conversation about greatest starters of all time, yet in just two solid years for the Rangers, he positioned himself for a payout that was several times greater than what he would have received had he never been shifted to the rotation.

That, in turn, explains the appeal for the Red Sox of exploring the possibility of moving Alfredo Aceves and Daniel Bard from the bullpen to the rotation. At a time when the Red Sox, for all practical purposes, feature at least three holes -- two in the rotation and at least one in the bullpen -- with Bard and Aceves representing two solutions, the cost of adding a top reliever in free agency or a trade would be a fraction of the cost of adding a top-flight starter.

Of course, Bard and Aceves also represent relatively inexpensive solutions to closing, but the potential value is always going to be greater for a starter than a reliever.

That notion helps explain why Wilson’s Rangers have become industry trend-setters. In the last four years, the team has shifted Scott Feldman (in 2008), Wilson (in 2010) and Alexi Ogando (2011) from the bullpen to the rotation with striking success. (Last winter, Texas also contacted then-free agent Bobby Jenks to see if he was open to joining their rotation. He instead chose to sign with the Sox as a setup man.)

Feldman was 17-8 with a 4.08 ERA in 2009; Wilson logged over 200 innings in each of the last two years while going 31-15 with a 3.14 ERA; Ogando was 13-8 with a 3.51 ERA in 169 innings a year ago. Now, with Wilson departing, Texas plans to shift Neftali Feliz from the role of closer to rotation.

The conversion path has played a key role in allowing the Rangers to build elite pitching staffs that have been good enough to take Texas to the World Series in back-to-back seasons. They have not had a single starter with a salary of more than $9 million in those two years, yet they have been able to assemble rotations capable of competing deep into October.

How significant has it been for the Rangers to be able to shift relatively inexpensive relievers into the rotation while avoiding free agency?

“It’s huge. It’s huge. Any time you’re able to fill one of those positions with someone who’s pre-arbitration in earning capacity and get above-league-average performance out of it, it’s a tremendous boon,” Rangers assistant GM Thad Levine recently said. “We had looked at what the Orioles did back in the day and what Houston had done in terms of breaking in pitchers in the bullpen and then transitioning them. It was something that we’d explored and evaluated.

“I wouldn’t say it’s a strategic blueprint that we had. Feliz is the one guy that we developed as a starter. We always envisioned him coming into the rotation. [Wilson] obviously had [started] in the minor leagues. Feldman had done it to a certain extent. Ogando had really been primarily a length reliever.

“I wouldn’t say it’s exactly a blueprint, but it’s something we’ve been open-minded to, and our goal has always been to get the best arms into the rotation at some point if our scouts felt they were capable. Philosophically, we were always open-minded.”

Whether coincidence or not, in light of the Rangers’ success, several other teams have now become similarly open-minded to the idea of moving top relievers into the rotation. The Blue Jays committed to having Brandon Morrow become a full-time starter. The Orioles are considering a rotation move for their top reliever, Jim Johnson. The Royals are going to see if All-Star reliever Aaron Crow can start.

That is the position in which the Red Sox now find themselves with Bard and Aceves. The team has told both right-handers -- their top two returning relievers from a year ago -- that they should prepare to come into spring training to compete for roles in the rotation. Both will get starters’ innings during the Grapefruit League season; then, at some point in camp, the team will decide whether the two pitchers will enter the season as starters or relievers.

The team had already made that determination with Aceves. More recently, after sitting on the fence, the team offered Bard similar direction.

“He’s going to be penciled in to be one of those guys who works going from his bullpen to pitching two innings to pitching four innings to pitching six innings,” Sox manager Bobby Valentine said earlier this month. “Whenever we get to that plateau, with the pitching coach I’ll hopefully have by my side soon, and all the members of the staff and front office, we’ll have to make a determination after that 18-20 inning mark as to where he will be during the season. I told him to prepare to be a starter and if that, in fact, does not happen to be ready and willing to be our closer.”

In a vacuum, the decision seems like a no-brainer. In practice, it is anything but. Here is a look at some of the dimensions that will govern what the Red Sox ultimately end up doing.

WHY THE RED SOX ARE CONSIDERING THIS

Beyond the idea that they could be cost effective options, both Aceves and Bard have arsenals that would seemingly work as starters. Bard has relied primarily on his fastball and slider as a reliever; those two pitches, more often than not, have been good enough for him to dominate.

But he is not just a two-trick pony. Bard has long had a changeup at his disposal (“There were points in college,” former UNC teammate Andrew Miller noted during the season, “when his changeup was probably his best off-speed pitch”), and over the last couple years, he’s worked to refine it.

“He’s got a changeup that’s been good. He’s been in situations at times where he hasn’t really needed to use it, but there have been outings where he has used it and it’s been really good,” said Sox GM Ben Cherington. “Certainly the reps that you get as a starter in spring training and the time in-between would give him a chance to work on that more.

“He certainly has a lot of the characteristics we think that go into a good starter. But most importantly, I think his mindset is in a good place. ‘Hey, I’m prepared to do this, and also prepared to pitch in a different role on Opening Day if that’s what the team needs.’”

Aceves, meanwhile, has a four-pitch mix that allows him to maintain his effectiveness against hitters from both sides of the plate. His combination of a fastball, cutter, curve and changeup allowed him to hold right-handers to a .216 average and .656 OPS; lefties hit just .190 with a .576 OPS against him.

“He’s got enough stuff. The key to being a starter is to go deep into the game and make sure you have enough stuff to keep getting them out. With his array of pitches, he can,” Aceves’ agent, Tom O’Connell, said at the winter meetings. “Great relievers are two-pitch guys. Most great starters, they have a variety of three or four pitches they can throw for strikes in any count and any situation. Obviously, Aceves has that. I think he has the stuff to be a very successful pitcher.”

Both also feature sturdy pitchers’ frames and the disciplined workout routines to permit them to make the transition to the rotation and withstand the rigors of a long season.

Moreover, Aceves and Bard are open to the idea of starting, something that is an essential element of a potential conversion. After all, in 2007, the Sox scrapped their exploration of a potential shift of Papelbon to the starting rotation because he informed the team that he was born to close. Given that Papelbon was passionate about his role, represented a known quantity out of the bullpen and the team did not have an identified closer, the conversion project was dismissed.

Aceves, in contrast, has said repeatedly that he wants to be a starter, and Bard has stated his desire to assume a role of growing importance, whether starting or closing. Moreover, he took the initiative to tell the Sox that he would embrace the idea of starting.

“I told [GM Ben Cherington] when I heard that [John] Lackey was having surgery and [Tim Wakefield] was a free agent, that I saw two openings in the starting rotation,” Bard said on this podcast.

“I hadn’t said it much, but in my own head, watching the guys in this league that had a lot of success in a starting role that I [thought I] could do that.  You know, I’ve got as good of or better raw stuff than them and I try to keep myself in good shape and it pointed to me having success in that role.  So I told Ben that, and Pap signed with the Phillies, maybe a week or two after that, I figured that maybe that whole starter thing would subside and maybe to forget it even happened.  And I figured that once Pap was gone they wouldn’t be taking me out of the pen but it turns out they feel pretty strongly about me becoming a starter and I do, too, and as of right now it’s that way.”

That open-mindedness served as an important checkmark in the potential move.

THOUGH BARD AND ACEVES FIT THE STARTER’S PROFILE, THERE’S PLENTY OF UNCERTAINTY ABOUT A MOVE

Both Bard and Aceves were, for most of 2011, dominant in their roles. If they returned to the bullpen next year, the Sox would view them as bullpen anchors capable of inspiring confidence in the team’s late-innings march. Though there is some element of the unknown with the possibility of a shift from setup man to closer for Bard, the right-hander has come into so many games with the outcome hanging in the balance that the Sox would have ample reason for confidence in his ability to adapt.

The transition to a starting role would be far more dramatic, with far less certain results. As one competing talent evaluator noted, with Bard, the Sox would be taking a certainty and moving him into a gray area. The payoff could be ample, but it could also leave the Sox short-handed in both the rotation and the bullpen.

How will a pitcher handle the second time through the order? How will he perform while regulating his time on the mound rather than emptying the tank in a max-effort undertaking? How will he withstand the rigors of the season when the dog days arrive?

“The unknown of durability is going to remain with anyone, whether it be Feliz or anyone who transfers from the bullpen to the starting staff,” said Valentine. “You can judge his pitches in spring training and you can judge his success, but it's very difficult to project the endurance of that success throughout a game. So that's a challenge.”

THE EVALUATION IS ALSO CHALLENGING

Conventional wisdom in baseball is that the worst time to evaluate players is in spring training and in September. In both settings, the quality of competition is diminished by the absence of competitive stakes (for both teams in spring training, sometimes for one or both in September).

Yet in making a decision about whether Aceves or Bard is suited to join the rotation, the Sox will have only the ample evidence of what they’ve done in their relief careers and a brief snapshot of how they perform as starters in spring training.

The Sox also have a handful of starts from Aceves in 2011 to factor into the judgment. The last time he was a full-time starter was in the minors in 2008. Bard was a full-time starter in a disastrous first pro season in 2007; he hasn’t appeared in the rotation since then.

The challenge of evaluating a pitcher’s fitness for a role in spring training, Valentine said, is “very, very difficult.”

“Spring training is a very deceiving part of the season.  Not only are they day games, but it's not always ‘A’ lineups,” noted the Sox skipper. “As you're trying to get guys to develop new pitches, often it doesn't come with success. Sometimes guys will pitch their 28 innings or 30 innings in Spring Training and not have the kind of success you want, but still, you believe that they could be a quality starter. I think it's all the stuff about experience that helps make those decisions. But again, it's going to be individual, unique. …

“Mistakes are made out of Spring Training, and that's why we play 162 [regular season games], so we can continue to make adjustments.”

THE INNINGS BUMP

Bard has never logged as many as 100 innings in a professional season. Indeed, since he pitched just over 90 innings in his first pro season in 2007 (between two levels of A-ball and the Hawaiian Winter League), he hasn’t even logged as many as 80 frames in any of his last four years.

That, in turn, led one talent evaluator from an AL club to hypothesize that it could take the Sox two years to build Bard up to withstand as many as 160-180 innings as a starter. If Bard becomes a starter and if the Sox treat him, for all intents and purposes, like a pitcher in his first pro season as a starter, then he might be targeted for 130-140 innings on the season.

A couple factors would be in play with such an approach. Teams want to make the increased innings workload manageable in order to try to avoid risk of injury. Further, there is also caution about overworking pitchers to the point where their effectiveness wanes down the stretch. A year ago, for instance, Ogando had a 2.88 ERA for the Rangers through early August; over the final two months of the season, that mark roughly doubled to 5.73.

Aceves would be in a somewhat different boat. He threw 122 innings last year between the majors and minors, and as recently as 2008, he logged 170 innings in four stops in the Yankees system, so while the Sox would face some restrictions in his innings bump, in theory, the team might be more comfortable turning him loose than Bard.

Age could also play into a somewhat more liberal approach than might otherwise be the case for the two pitchers. Aceves just turned 29; Bard will be 27 next season. While teams typically are careful to limit an innings increase to roughly 20 percent a year among young pitchers, the fact that Bard and Aceves will both be in their late-20s could allow the Sox to loosen the reins a bit.

Ogando went from 72 to 169 regular-season innings from 2010 to 2011 (when he was 27). Wilson went from 73 innings in 2009 to 204 as a 29-year-old in 2010. Feldman went from 69 innings in 2007 to 164 in 2008.

“There’s no right or wrong answer. I will say that the three guys we did it with – Feldman, C.J. and Ogando – were all a little bit older, a little bit more mature,” said Levine. “Feliz will be slightly different because he’s younger, because we don’t quite know what impact that will have, but the other three guys we were more confident because they made the transition when they were older.”

For a Sox-specific example, it's worth recalling that a decade ago, the team transitioned Derek Lowe from the bullpen (where he spent most of 2001, a year in which he logged 91 innings) to a full-time starter as a 29-year-old in 2002, a role in which he logged 219 innings, finished third in AL Cy Young voting and became one of the foremost workhorses in the game.

So, while there is an assumption that there would be significant innings restrictions on a pitcher making his first move to the rotation, pitchers can blow past perceived workload limitations.

CONVERTING A STARTER -- OR TWO -- LIKELY REQUIRES THE REST OF THE PITCHING STAFF TO SHOULDER AN EXTRA LOAD

Rotation depth is always an important consideration, even for teams that feel like they have five starters capable of delivering 180-200 innings. Injuries will almost always impact starters at different points in the season; when that happens, the importance of solid fill-ins to helping a team avoid calamity is significant. (See Sept. 2011 for recent proof from the Red Sox.)

It’s one thing to have depth to respond to the occasional, unexpected crisis. It’s quite another to have a need for depth built into the structure of a pitching staff.

As Wilson demonstrates, a pitcher who shifts from the bullpen to the rotation doesn’t necessarily have to face notable restrictions. Even so, there is a likelihood that they will be unable to work as deep into games as regularly as career-long starters. Moreover, there will likely be occasions when they are skipped.

In other words, a team has to account for the fact that newcomers to the rotation may face workload restrictions. That means more starts for pitchers who don’t open the year in the rotation; it means more innings for the bullpen to pick up a starter who is limited (by design at times) to five innings or so.

That being the case, the Sox acknowledge that there would be challenges if they were to commit to converting two pitchers from the bullpen to the rotation.

“It’s part of the calculus, certainly, figuring out how the pitching staff works, not just can they do it from a talent standpoint, but here are the innings we have to fill over the course of a 162-game season and do we have enough to fill it?” Cherington acknowledged.

THAT SAID, THE RED SOX ARE COMFORTABLE WITH SOME RISK IN ROUNDING OUT THEIR ROTATION

Yes, the Sox have limited resources to spend. But there was something else noteworthy in Sox GM Ben Cherington’s recent explanation of why his team did not pursue Japanese starter Yu Darvish this offseason.

“With [Josh] Beckett, [Jon] Lester and [Clay] Buchholz in place at the top of the rotation, we don’t feel like we’re backed into a place where we need to break the door in for a top-of-the-rotation starter,” Cherington said in an appearance on SiriusXM MLB Network Radio. “If we can do that and it makes sense for us, then we’ll certainly do that. We’re always looking for ways to do that. But with Beckett, Lester and Buchholz here in our rotation, we’re in good position there and can kind of let the market come to us a little bit.”

The notion of gambling on Bard and/or Aceves -- taking what is a reliable part of the pitching staff and willingly assuming some risk -- is possible for the Sox because they believe they have three anchors who can give them reasonable stability for such experiments. In theory, the presence of Beckett, Lester and Buchholz -- assuming that all three are healthy -- would leave the team in solid shape even while pitchers work through growing pains associated with a transition.

THE FACT THAT DANIEL BARD WILL BE PREPARED AS A STARTER DOES NOT MEAN HE WILL BE A STARTER

This was, in essence, a decision without real consequence. Bard’s offseason program will be tweaked slightly. But the decision to have him prepare to compete for a rotation spot, in its own right, means nothing.

Jonathan Papelbon came to spring training in 2007 as a starter. He left as a closer. Ditto Neftali Feliz with the Rangers last year.

This is an experiment based on the fact that the Red Sox have needs in both the rotation and bullpen. Bard will likely be used wherever the need is greater. If the starting alternative to Bard is less reliable than the relief alternative to Bard, then the Sox likely would keep their rocket-armed right-hander in the rotation.

But if the Sox do not have an apparent lockdown option for the ninth inning as spring training winds down, it would not come as a real surprise if the Sox elected to insert Bard as their closer, so long as they have viable, serviceable options for the rotation.

The Sox’ offseason approach to their pitching staff has been focused on giving the team flexibility to respond to the offseason market. The potential versatility to use Bard or Aceves -- or, for that matter, Felix Doubront or Andrew Miller or even, should the situation arise, Alex Wilson -- as a starter or reliever allows the Sox to take a flexible approach to all of their offseason plans, and, as Cherington suggested, let the market come to the team.

Teams face the possibility of very bad decisions when they are backed into a corner and make moves out of necessity. The mere suggestion that the team has notable in-house candidates who can address the team’s rotation or bullpen needs ensures that the Sox can choose their opportunities in the trade or free agent market. It's akin to existential deterrence in the Cold War: Whether or not Bard or Aceves ends up starting, the mere possibility that the Sox might use either pitcher in the rotation looms over their discussions of moves for pitchers this offseason.

The Sox, at least in theory, can choose whether to add relievers or starters, based on the opportunities offered by the market. Their negotiations will not be hemmed in by plainly apparent needs.

In that sense, the discussion about the pitchers' potential to work in the rotation represents an enormously impactful element in the construction of the 2012 roster -- something that will remain true even if both pitchers ultimately end up back in the bullpen.