A night when Scott Atchison was on the mound as the pitcher of record for the Red Sox in one of their biggest losses of the season offered a reminder. In spite of all the injuries that have altered the composition of the Sox, bullpen performances have played a pivotal role in determining the shape of the division. 

In that regard, it is fair to wonder whether any newcomer to the American League East had as big an impact in 2010 as Rafael Soriano.

One can make a case for Red Sox third baseman Adrian Beltre or even Rays setup man Joaquin Benoit. Even so, the argument for Soriano is compelling – particularly given the fact that, at the start of last offseason, the Sox and Yankees were among the many clubs that at least checked in on the asking price for the hard-throwing right-hander when he was a free agent.

WHAT HE HAS BEEN

The Tampa Bay right-hander has been a force as the closer for the Rays, who after Saturday’s 3-2 victory over the Sox are tied atop the AL East with the Yankees, and 5 ½ games in front of Boston. Soriano’s 1.75 ERA is the second lowest among American League pitchers with at least 50 innings. He leads the majors with 38 saves. He has converted 95 percent of save opportunities, second in the majors.

(Even that understates his dominance: in one of his two blown saves, he entered in the eighth-inning with a one-run lead and runners on the corners. He struck out the first batter, then induced a double-play grounder; but the ball was thrown away, allowing the tying run to score.)

Opponents are hitting just .172 against him, with right-handers having been limited to a microscopic .133 mark.

In the process, Soriano has made one of the Rays’ foremost weaknesses of a year ago one of their greatest strengths. In 2009, Rays relievers had a 3.98 ERA, seventh in the American League and 17th in the majors. The Rays blew 22 saves, and had a 65 percent save conversion rate, slightly below the league average of 67 percent.

This year, Rays relievers have a 3.27 ERA, tied for the best mark in the American League and tied for third best in the majors. Thanks in no small measure to Soriano’s dominance, the Rays have converted 80 percent of save opportunities, tops among big league clubs.

Given the Sox’ bullpen struggles to find an effective complement to Daniel Bard and Jonathan Papelbon this year, the team could be forgiven if they had wondered more than once what might have been if Soriano had been one of their relievers.

A LOOK BACK AT HIS OFFSEASON AVAILABILITY

As the Braves’ closer in 2009, Soriano recorded 27 saves, a 2.97 ERA and a head-spinning 102 strikeouts in 75.2 innings. His swing-and-miss stuff had nearly universal appeal.

More than 20 clubs showed some level of interest in the right-hander after he became a free agent last offseason. The Orioles had heavy interest before signing Mike Gonzalez, and the Yankees and Red Sox both checked in about the possibility of adding Soriano as a setup man.

Soriano, according to industry sources, did not rule out the possibility of working as a setup man. He felt that, for the right multi-year deal, he could serve a meaningful late-innings role and then, perhaps, take over for a team’s established closer down the road, confident that he could repeat a progression he’d followed in Atlanta. 

But then, the Braves -- wanting to claim a couple of draft picks as compensation (including a first-round pick from any team that signed him) for the Type A free agent -- offered him arbitration, despite signing Sox reliever Billy Wagner to a one-year, $6.75 million deal to close for them.

And most of the preliminary conversations that Soriano had been having with other clubs stopped. With the free-agent market filled with uncertainty, and closers signing for relatively short money, the right-hander elected to accept arbitration.

“Boston, the Yankees, a lot of teams wanted me, but they didn’t want to give up the first-round pick. That’s what my agent told me,” Soriano recalled during spring training of the days leading up to the Dec. 7 deadline to accept or decline arbitration. “I was sitting a long time [after the arbitraton offer] and [my agent] said, ‘You’ve got to do something. It’s close to midnight, and we’ve got to find out what you’re going to do.’ That’s when I accepted arbitration with Atlanta.”

WHY HE’S NOT A RED SOX

While the Sox had at least reached out to gauge Soriano’s asking price as a free agent, their pursuit of him never became serious, according to multiple industry sources. The team felt that their resources during the offseason were better spent elsewhere, chiefly on the likes of John Lackey, Mike Cameron, Marco Scutaro and Adrian Beltre.

And at the time, it would have been difficult to fault such a stance. The team had an established closer in Jonathan Papelbon, an up-and-coming bullpen star in Daniel Bard and a trio of pitchers – Ramon Ramirez, Manny Delcarmen and Hideki Okajima – with significant and recent track records of success (even though they had shown signs of vulnerability at the end of 2009).

Given what they had, it would have been difficult for the Sox to justify a multi-year deal for $6-7 million a year even had the Braves not offered Soriano arbitration.

Certainly, the Sox have shown a reluctance to prioritize spending on middle relief. The most the team has guaranteed a middle reliever (in average annual value) was the two-year, $6.7 million deal (that included a $3.85 million option) to which it signed right-hander Julian Tavarez prior to the 2006 season.

So, as fascinating as it is for the Sox – or any other team, for that matter – to wonder what their bullpen might have looked like with Soriano, a deal with the reliever was always highly unlikely.

UNEXPECTEDLY, A RAY

The Rays never thought that they would be in a position to take Soriano, either. Tampa Bay is philosophically opposed to expensive, multi-year deals for closers, and when Soriano was a free agent, it appeared that he would require just such a contract.

But an unexpected sequence of events dictated that he ended up going from Atlanta to Tampa Bay in exchange for reliever Jesse Chavez (whom the Rays had acquired earlier in the offseason as a mid-level prospect from Pittsburgh in exchange for second baseman Akinori Iwamura).

Had the Braves elected not to offer the right-hander arbitration, thus chilling the free-agent market for his services, Tampa Bay never would have been able to acquire Soriano. Had Soriano not accepted, the Rays wouldn’t have pursued him at the expense of a first-round draft pick. 

But the Braves elected to offer Soriano arbitration, and Soriano elected to accept the offer. Atlanta immediately asked whether he would be open to a trade (Soriano’s approval was required for any deals before June 15), and the right-hander said that he would indeed be open to being shipped to another club.

Tampa Bay dealt for him, and Soriano quickly signed his one-year, $7.25 million deal. Though it was a one-year deal, rather than a multi-year contract for which he’d been hoping, it was a good outcome for Soriano on a few levels.

The deal was guaranteed, rather than an arbitration settlement that is non-guaranteed. It represented the second-biggest 2010 salary conferred on any free-agent reliever this past offseason, behind only the one-year, $8 million deal that Trevor Hoffman received to re-sign with the Brewers.

But, perhaps more importantly, Soriano landed in a situation that was ideal in Tampa Bay. He had the opportunity to close, and to do so in the most prominent division in the majors, thus giving him a chance to prove that his talents as a reliever could translate to any environment.

Soriano was not able to get the Rays to agree not to offer arbitration, a provision for which he and his agent were pushing in hopes of ensuring that the right-hander would avoid a repeat of the scenario that played out last offseason. But for Tampa Bay, such a clause would have been a deal-breaker given the way they valued draft-pick compensation for the reliever.

Given his performance this year, in which Soriano was named an American League All-Star, his position in the market would appear even better this coming offseason than it was last winter. Other teams would be more likely to sacrifice a draft pick to sign him based on what he’s now accomplished.

That said, the closer market took a noteworthy turn south this past offseason. After the 2008 season, Francisco Rodriguez received a three-year, $37 million deal from the Mets. Kerry Wood got a two-year, $20.5 million deal from the Indians. Brian Fuentes signed a two-year, $17.5 million deal with the Angels.

Last offseason, those types of multi-year deals simply were not available. And so, it remains to be seen what type of contract will be available for Soriano following his dominant year for the Rays.

But for now, none of that is terribly important. Of far greater relevance is the impact that he’s had on the American League East this year. And in 2010, Soriano has emerged as one of the key difference-makers in determining the balance of power in the AL East.