FORT MYERS, Fla. -- There were two things we knew definitively regarding Will Middlebrooks' situation Wednesday night: A potential loss of the third baseman would be one of the toughest for the Red Sox to digest, and the Red Sox hadn't yet been inclined to call Scott Rolen. (More on Rolen later.)

While February usually is full of hope and optimism when it comes to building baseball teams, it was common knowledge that the thinnest spot for the Red Sox entering spring training likely was at Middlebrooks' position.

With one check swing, a toss of the helmet and a frustrated walk into the clubhouse, the Red Sox were offered a reminder of their reality.

The 24-year-old surfaced concerns when he pulled up short on a swing against a Chris Tillman fastball, forcing Middlebrooks' right hand to awkwardly fly off the bat. Later, his injury was described by the team as "right wrist soreness," with that "right wrist" just happening to be the one that was fractured when he was hit by a pitch last Aug. 11.

For starters, this is what we had from Red Sox manager John Farrell after his team's game in Sarasota against the Orioles:

"We weren't going to take any chances here tonight. He felt better after he was examined here in the clubhouse. We'll get further tests on him in the morning to see what the next steps will be, but I think as the initial discomfort wore off, he felt pretty good about it. But like I said, how he gets examined in the morning will give us our next steps.

"Most importantly, the way he felt afterwards, and we'll get a better read on it tomorrow, but hopefully this is something that's just a short-term thing where he's day-to-day. But I think everyone saw last year, when he was missed in that lineup, that's a potent right-handed bat. Hopefully this is just a day-to-day type thing, and every indication is just that right now.

"What we'll check is just how he comes in in the morning. If we feel like there's overnight soreness or any kind of swelling, certainly every precautionary test would be done at that time. But everything was encouraging just based on the tests here tonight -- the manual tests.

"He felt almost like a zinging sensation that went down through the wrist. At that point, there was no reason to take any risks with the wrist whatsoever given what he went through last year with the broken wrist on the hit by pitch. It was just a matter of getting him out and getting him treated right now."

Regardless of the diagnosis -- either the initial go-round, or what will follow -- this is what we do know regarding Middlebrooks: He already has proven to be one of the most irreplaceable pieces of this lineup.

The Red Sox went 43-32 in games Middlebrooks played last season. And when he did not play? The team was 26-61, including 13-33 after he was hit by an Esmil Rogers ninth-inning fastball.

During Middlebrooks' active stint with the Red Sox, the offense carried a .753 OPS, ninth-best in the majors. After the season-ending ailment the lineup was second-to-last in the big leagues with a .659 OPS.

The answers were Pedro Ciriaco (35 games), Nick Punto (26), Danny Valencia (10), Mauro Gomez (9) and the trio of Mike Aviles, Ivan De Jesus and Nate Spears, who each played one game at third.

One season later, the backup plans haven't offered any sort of certainty.

Earlier in the day Wednesday, with Middlebrooks and Ciriaco scheduled to be the lone third-base options against the Orioles, another collection of candidates took grounders from Triple-A manager Gary DiSarcina on the JetBlue Park infield. Their names were Drew Sutton and Brock Holt.

Right now this is what the Red Sox have -- two guys who were thought to be competing for the utility infield job (Ciriaco and Holt) and another who has played 22 of his 105 major league games at third base, having never made it through an entire season without spending the majority of a campaign in the minors (Sutton).

While many in Boston were intrigued by Ciriaco's potential after a standout spring training (.429 batting average, 1.096 OPS) and first two months in the majors (.333/.801) in 2012, they forget his third month, when the average and OPS dropped to .217 and .522, respectively.

Holt offers some intrigue, a reason why he has been introduced to third base this spring (with the Red Sox having to sacrifice having a second baseman during their morning workouts Wednesday in order to facilitate the instruction). Looking like a combination of Matt Damon and Mark Wahlberg, Holt has hit .317 with a .381 on-base percentage and .427 slugging mark in parts of four minor league seasons. Playing in 24 games for Pittsburgh last September, he hit .292 with a .329 OBP.

And then there is Xander Bogaerts.

Many of those stung by the insecurities surfaced by Middlebrooks' mishap will immediately call for the introduction of Bogaerts, the organization's prized 20-year-old prospect. They won't care that up until he left to be with the Netherlands' World Baseball Classic team Saturday, he had taken a week's worth of grounders at third base. They won't care that it was the first time he had played the position since Little League, pointing to his advanced offensive skill set and increased experience at third thanks to the WBC. They won't care ... but the Red Sox will. With a good start in the minors, it is feasible to imagine a Middlebrooks-esque introduction into the majors for Bogaerts by the middle of '13, but anything else would appear to be a stretch.

If Jose Iglesias shows evidence this spring that he has made enough adjustments to offer adequate production as a hitter, perhaps the Sox could move Stephen Drew over to third. Drew has never played the position professionally, but during the offseason, teams had explored the possibility of playing the 29-year-old at the hot corner. Long term, if Middlebrooks was sidelined and if Iglesias' development was deemed acceptable, this actually might be the most palatable (albeit one of the least likely).

Outside the organization, options include Rolen, the 37-year-old free agent who issued this statement regarding his status: "Right now, I'm simply not ready to make a commitment. I would like to leave my options open, without closing any doors. I am looking forward to all of the challenges, both personally and professionally, I will face in the future."

According to a major league source, while the Red Sox haven't yet called on the veteran, there is a belief that he would be interested in talking shop with the Sox despite rumors of his retirement.

Rolen last played regularly for the 2010 Reds, making the All-Star team, earning a Gold Glove and finishing 14th in the National League MVP voting after hitting .285 with 20 homers and an .854 OPS. The last two seasons, however, he played 65 and 92 games, respectively.

Such an option as Rolen wouldn't be considered, however, unless further medical evaluation reveals a more ominous diagnosis for Middlebrooks than the one that had him, after strength tests (but without benefit of an X-ray or MRI), suggesting that there was no tear or break in his right wrist. One of the worst-case scenarios would be an injury to the ECU tendon, the same issue that struck Jose Bautista and David Ortiz. 

Said Dr. Christopher Geary, an orthopedist at Tufts Medical Center (speaking generally and without specific knowledge of Middlebrooks' injury): "[It's] unlikely he broke anything on a check swing. … Check-swing injuries always make me worry about the ECU tendon in the wrist -- that's what [Bautista] had last year. If it's torn or, more likely, unstable, they might try a period of rest and a splint or cast, but would likely need surgery and probably 4-6 months [to recover]. Best-case scenario is probably just a traumatic tendinitis, shut him down for a week to 10 days."

As a point of reference, Bautista suffered his injury last July, had surgery in September and has no restrictions this spring training. Ortiz' injury occurred in '08, with the designated hitter choosing a non-surgical approach. He returned for the final stretch that season but felt the effects of the injury straight through '09.

Rays outfielder Sam Fuld injured his ECU tendon in September 2011 on a check swing much like Middlebrooks' and passed initially on surgery. However, at the end of spring training last year, he re-injured the wrist and then did have to undergo a repair, requiring nearly four months on the disabled list while recovering.

Many of the scenarios might never re-enter into the Red Sox' conversation this season, with Middlebrooks still hitting the ground running come Opening Day. But until a thorough exam on Thursday gives the third baseman a clean bill of health, the team must consider not just the most likely scenario that Middlebrooks dodged a bullet but also the potential consequences if it turns out he did not do so. And so, until there is a definitive diagnosis, the team will be unable to exhale while contemplating the possibility of an injury to which the Sox lack an ideal solution. 

Alex Speier contributed to this report.