FORT MYERS, Fla. — The elements in Fort Myers conspired against Jonathan Papelbon on Sunday, with repercussions beyond a single bad day at the office.

At City of Palms Park, something was clearly amiss on Sunday morning when the Red Sox closer, in full uniform, lay down on the floor and tried to prop his head up on the bottom of his locker. The 29-year-old had felt a migraine coming on, and so the team’s medical staff had given him medication to stave off its symptoms.

The medicine did its job, preventing the migraine from hitting the pitcher with full force. But Papelbon was listless after entering the game. It showed, as he recorded just one out while allowing six runs (five earned) on five hits while allowing a walk and hitting a batter.

“It’s not like I felt like I had a migraine going into my outing or anything. It’s just that I was real lackadaisical, not much energy in me,” Papelbon said. “I’m really just trying to throw the ball in the zone and let players get themselves out. Unfortunately, they were hitting it hard around the whole ballpark.”

The onset of migraines are a fact of life, though Papelbon and the Sox medical staff have become better at regulating them to the point where they are far more manageable than they once were.

While the effort to do so clearly is imperfect, the migraines no longer come with the sort of repercussions that they did just a few years ago.

While Papelbon found himself facing a challenging present, on the other side of Fort Myers, another development was taking place that could have implications for the closer’s future.

Twins closer Joe Nathan, after trying to throw for the first time since tearing the ulnar collateral ligament in his right elbow on Saturday, recognized that he would not be able to pitch without undergoing Tommy John surgery. He will have surgery and miss all of the 2010 season.

That, in turn, could have some bearing on the financial future of Papelbon. The Red Sox and Twins closers, after all, have been virtual clones over the past four seasons, since Papelbon took over ninth-inning duties for the Sox.

During that time, the two pitchers have led the majors in ERA, opponents’ batting average, opponents’ OBP and opponents’ slugging. Their performances are almost impossible to distinguish:

Papelbon: 1.74 ERA, 151 saves, 10.6 Ks per 9 IP; opposing hitters have a line of .190/.243/.284/.527 against

Nathan: 1.73 ERA, 159 saves, 10.9 Ks per 9 IP; .180/.241/.285/.526

That being the case, when it comes time for Papelbon — who has a one-year, $9.35 million deal for the coming season — to explore the market for a long-term deal (whether while still under the control of the Sox between now and the end of the 2011 campaign, or as a free agent following next year), Nathan would seem an obvious basis for contractual comparison.

And the Twins closer’s four-year, $47 million deal represents a market standard, as his contract represented the most amount of guaranteed money ever conferred upon a reliever.

Nathan’s performance had put him in position to enjoy such a payday. But now, his injury will represent yet another cautionary tale about long-term deals for relievers. Even though Nathan, like Papelbon, is so good that he has defied the year-to-year volatility of performance by relievers, he underscored the challenges endemic to keeping relievers healthy for the long haul.

There have been 12 multi-year deals of at least $9 million a year signed by closers. Three of the pitchers to sign those contracts (Nathan, Billy Wagner, B.J. Ryan) have been subjected to Tommy John surgery, and a fourth (Eric Gagne) also underwent a major procedure that left him unable to pitch for most of the two years of his deal.

Seemingly, it represents a significant — and risky — leap of faith to assume that a closer can remain intact during the life of his deal. After all, on March 5, Twins manager Ron Gardenhire was offering his hope that Minnesota could keep Nathan healthy for the coming year, following an offseason in which he had surgery to remove bone spurs and loose bodies from his elbow.

“[Keeping closers healthy] just depends on how you use them. If you’re going to take a closer and start stretching him out to two innings here, two innings there, save 50 games a year, you’re going to wear a guy out pretty quick,” Gardenhire said. “We’ve been fortunate enough to give him one inning at a time rather than the two.

“Last year we were in a battle for our lives. The only way we were going to make it, we stretched him out a little bit. You know what? He was still as good as they get, and he will be, if you take care of him.”

One day later, Nathan blew out while pitching in his first game of the spring against the Red Sox.

The Minnesota closer will only offer further resistance to long-term deals for the pitchers who helm the ninth inning. Injuries are one issue. The typical year-to-year performance swings of all but a short list of pitchers is another. So, too, is the fact that alternatives often are available should a closer be lost.

Indeed, the idea that it is not terribly difficult to find an alternative to handle a game’s final inning is something that makes it unlikely that a closer will ever see another five-year deal.

Only one such deal has ever been signed, by B.J. Ryan with the Blue Jays. Ryan needed Tommy John surgery at the start of the second season and has subsequently been released by Toronto after having given them only two healthy years for $47 million.)

Since the start of the 2006 season, only one closer (Francisco Cordero of the Reds) has received a deal of at least four years with an AAV of at least $9 million. Cordero’s deal, according to multiple industry sources, likely will set the benchmark for a Papelbon deal at four seasons, but no one anticipates a deal exceeding that in years.

“Closers are so replaceable,” said one talent evaluator. “But I guess it only takes one team [to change the market].”

If anything, the industry could be moving in the other direction. Francisco Rodriguez signed a three-year, $37 million deal following the 2008 season, following a year in which he set a big league record with 62 saves. Nathan’s injury surely will give front offices further cause for pause.

That will likely be true even of Papelbon. The Sox closer has been a model of health for more than three years now, but the shoulder subluxation that he suffered in September 2006 has not been forgotten by talent evaluators around the game.

Still, despite any lingering injury concerns, perhaps Papelbon will represent a special case whenever it does come time for him to sit at the negotiating table to consider a long-term deal. He is, after all, one of three pitchers (along with Hall of Famers Addie Joss and Ed Walsh) with a career ERA under 2.00.

“That’s something that’s near and dear to me,” Papelbon said earlier this spring. “I feel like the amount of saves you get is kind of overrated in a sense. You could end up with 40 saves a year and have a 3.50 ERA. I think it’s harder to have 38 saves, with three blown, and an ERA that’s sub-2.00.”

Such performance could put Papelbon in a special class when it comes time for him to secure his future. Assuming that he can sustain his level for the next two years, based on career numbers, he has the historic backing to suggest that he deserves as much as — if not more — than any closer in history, or at least anyone not named Rivera.

But the industry may not reward him as such. The injury to Nathan served as yet another warning sign that Papelbon belongs to a high-risk occupation. That, in turn, could impact his earning power down the road. It was, in short, a dark day for two exceptional closers who share a city of residence during the spring.