It’s now been almost a week since the Red Sox and Pirates completed a six-player deal headlined in both Boston and Pittsburgh by the relocation of closer Joel Hanrahan to the Sox. Hanrahan is now expected to anchor a seemingly deep Red Sox bullpen, taking over for (displacing?) Andrew Bailey in the ninth inning as the last line of defense when the Sox have a lead.

Plenty has been written about Hanrahan. Yet in some respects, the most interesting player in the deal from the Sox’ perspective is not one whom they acquired but rather one with whom they parted.

In 2008, the Red Sox were ready to walk away from the deal that would have sent Manny Ramirez to the Dodgers and that brought Jason Bay to Boston over right-hander Stolmy Pimentel. At the time, he seemed to represent too significant a prospect to concede to the Pirates in the trade, too promising a future big league starter.

That was when Pimentel was a precocious 18-year-old with the Lowell Spinners, the youngest starter in the New York-Penn League, holding his own against much older competition. He continued to look like an excellent prospect given his age and stuff (slowly developing velocity that built into the mid-90s, a swing-and-miss changeup and the potential to spin an average breaking ball) for the next two seasons, resulting in his addition to the 40-man roster as a 20-year-old after the 2010 season.

But then his prospect status took a major hit in 2011. Pimentel entered the year ranked as the No. 6 prospect in the organization, as rated by Baseball America; he finished it ranked No. 23 after going 0-9 with a 9.12 ERA in 15 starts with Double-A Portland, resulting in a demotion back to High-A Salem, where he went 6-4 with a 4.53 ERA. He showed velocity (his fastball bumping as high as 97 mph as a starter) that year, but little else, as mechanical struggles flattened his fastball and rendered his changeup ineffective.

The Sox remained hopeful that adversity in 2011 would translate to an important foundation for 2012.

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Back in Portland last year, Pimentel did show considerable improvement, making his delivery more compact in an effort to harness his improved velocity while also showing flashes of the old changeup. Still, his performance proved inconsistent en route to a 6-7 record and 4.59 ERA. He struck out 6.7 batters and walked 3.3 per nine innings.

There were flashes of the ability to dominate older hitters in the Eastern League (for instance, he gave up just two hits in six shutout innings in his last start of the year, completing a four-start cycle where he had a 1.23 ERA). But those were intermingled with train wreck outings that inflated his numbers and raised questions about his ability to compete on a consistent basis.

The Sox remained upbeat about Pimentel’s prospect status, with some suggesting that the path of a pitcher whose results did not yet match his stuff reminding them of Felix Doubront. Still, it was impossible to say whether, in 2013, he would make enough progress to stick on the big league roster by the time he was out of minor league options in 2014.

Meanwhile, a host of Red Sox pitchers zoomed by Pimentel in the organization’s depth chart. The right-hander, still viewed as promising, had become expendable.

Yet the trajectory of Pimentel, in some ways, was less interesting for the path that he traveled than in what it said/says about the Red Sox farm system that he leaves behind. There are a few important messages in Pimentel’s arc.

Among them:

PROSPECTS STRUGGLE AND FAIL

The Red Sox farm system is in its best shape in years. Numerous players have graduated to the upper levels while showing the potential to be impact players at the big league level.

But not all of them will reach the big leagues on their projected timetables, if at all. Players endure unexpected years in which their seasons go completely off the rails, requiring a fairly dramatic recalibration of their futures. Those bad years do not necessarily portend the end of their prospect status, but they do necessitate a recalibration of expectations and plans.

Back in 2008 and 2009, it seemed reasonable to project Pimentel as a member of the rotation as early as 2012, and almost certainly by 2013. Obviously, that didn’t happen.

He may still develop into a mid- to late-rotation starter with the Pirates -- and based on the progress he made with his delivery in 2012, along with Pimentel’s intelligence, work ethic and youth, it would be a mistake to rule out a developmental leap -- but he’d fallen in the Sox pitching prospect pecking order to a point where he was no longer a deal-breaker.

When the dust settles, and clarity emerges regarding the current Red Sox prospect class -- particularly with pitchers like Matt Barnes, Allen Webster, Rubby De La Rosa, Henry Owens, Brandon Workman, Drake Britton, Anthony Ranaudo, Brian Johnson, Pat Light, Frank Montas or others -- there will be plenty of additional stories of players who struggled, who needed an extra year or two or three in their progression before establishing themselves as big leaguers, rather than making steady level-a-year movement up the ladder. Some will never make it.

That’s why this offseason for the Sox represents more than just a bridge. It’s also a hedge.

The Sox believe that a number of players in their system will become successful. But they recognize that it would be a fool’s errand to go all-in on that notion. And so, the acquisition of free agents on one-, two- and three-year deals also gives the team leeway to react and adapt if/when prospects falter.

The team loves Jackie Bradley Jr. Some scouts outside the organization think he would be big league ready in 2013. The Sox project him as an everyday center fielder for 2014.

But what if he’s not? What if he suffers an injury next year in Portland, or gets overmatched in Triple-A Pawtucket? The Sox aren’t expecting either to happen, but the front office remained mindful of those possibilities in reaching a three-year deal with Shane Victorino, who gives the team insurance should Bradley hit a hiccup and Jacoby Ellsbury depart as a free agent. Ditto the two-year deal for Ryan Dempster, which buys additional time for 2014 if pitchers like Webster, De La Rosa, Barnes, Ranaudo, Britton and/or Workman are not ready.

In short, the team knows that it will need to graduate impact big leaguers from its current crop of prospects, but Sox officials are also mindful that even top prospects struggle and fail. They’ve seen it with Pimentel; they’ve seen it with plenty of other prospects. When it comes to minor leagues, no matter how glimmering the promise, there are almost never sure things.

THE IMPORTANCE OF PROSPECT VOLUME (AND WHAT DEALING PIMENTEL SAYS ABOUT THE STATE OF RED SOX PITCHING DEPTH)

A couple years ago, the inventory of pitching prospects beyond Pimentel appeared thin. The idea of trading him seemed difficult to fathom given the absence of obvious big league starters elsewhere in the system.

That is no longer the case. One year after the Sox had almost no homegrown starters in Triple-A, the team will have a pretty deep pool of starting prospects in the upper minors. In Pawtucket, the rotation to start the year should feature De La Rosa, Webster, knuckleballer Stephen Wright and left-hander Chris Hernandez, perhaps along with left-hander Drake Britton. In Double-A, the team will have Barnes, Ranaudo, Workman and perhaps Britton.

That’s eight potential big league starters -- ranging from potential front-of-the-rotation guys like De La Rosa, Webster and Barnes to pitchers with more modest profiles such as Hernandez, whom most view as a potential spot-starter or left-handed reliever -- in the upper minors. All of them have multiple options remaining. (Pimentel, it’s worth noting, had just one option left for 2013.)

Simply put, Pimentel had been surpassed by a number of pitchers who represent what appears to be a current organizational area of strength. The Sox were positioned to deal him not simply because his prospect stock had fallen, but also because that of a number of his organizational peers had risen. Instead of representing one of a few potential starters, he represented one of many.

PIMENTEL LIKELY WON’T BE THE LAST RED SOX STARTING PROSPECT TO GO

For much of the offseason, it’s seemed as if the Red Sox were hoarding their prospect inventory. At a time when the Blue Jays have been making a considerable bet on the next couple years with their big league club, shedding a wealth of prospects to acquire players like R.A. Dickey, Josh Johnson, Jose Reyes and Mark Buehrle, the Sox have made just the Hanrahan trade while signing a bunch of free agents to short-term deals.

But that doesn’t mean that the team hasn’t been willing to move prospects. It just hasn’t found the right deal.

The Sox were open to dealing some of their top minor league talent for Reyes, before he went to Toronto as part of the blockbuster package. And they remain willing to deal top prospects going forward in order to get the right piece or pieces back.

The players who went to the Pirates for Hanrahan -- Mark Melancon, Jerry Sands, Pimentel, Ivan De Jesus Jr. -- all had relatively modest value to the organization. But there will come a point, team officials anticipate, when they will be asked to dip into their higher-end talent, and when the goal of playing in the postseason will require the team to deal from the cream of its prospect crop. And even in that regard, the team has positioned itself fairly well, particularly given pitchers like De La Rosa, Webster and Barnes, who carry considerable value not just to the Sox but also to the industry.

In other words, the fact that the Sox haven’t parted with top prospects this offseason doesn’t mean they won’t do so going forward. In that respect, Pimentel may represent a modest harbinger of other deals to come, if not this offseason then in coming seasons or offseasons. In the end, the idea of team control of young, inexpensive, talented players is appealing, but the ultimate goal is to field a major league team capable of winning championships, not simply harboring prospects for a future that may or may not arrive.