Which prospects could the Red Sox call up in September?

September is such an odd month for baseball. It contains the last regular season games of the year, the final chances for teams in the playoff race to make their cases on the field, but it also features completely different roster rules than every other month. Rosters expand on September 1, allowing the entirety of a club's 40-man roster to join the big-league squad and change the complexion of a team.

Now, not every member of the 40 makes it to the bigs -- some are not even at the point where a cup of coffee in the majors makes sense, or maybe there isn't any room on the roster for players of a certain position. The Red Sox should call up a few players on their 40, though, once the September opportunity comes around.

Jackie Bradley Jr.

Bradley has already been in the majors a few times in 2013, as he was in the Opening Day lineup and has come up as an injury replacement on a couple of occasions. While he wasn't quite ready for the big leagues earlier in 2013, September might very well be his final introduction to the level, as there should be an opening somewhere in the 2014 outfield for Boston's top outfield prospect.

He won't be auditioning for that role with a September call-up, though, not unless injury strikes somewhere between now and then. Bradley is more likely to play the role of defensive substitute with the occasional pinch-running moment, and a start thrown in here and there in order to get the regulars some rest. He'll have his uses, but this call-up will, in a lot of ways, be about getting Bradley into the major-league culture on a regular basis, without the same worries of being demoted that might have existed in his past trips.

Xander Bogaerts

It's assumed that Bogaerts will get to make his major-league debut in September, with the hope being that it's in a no-pressure spot, and not because Will Middlebrooks has failed to take his recent minor-league success with him to Boston. He's not on the 40-man roster, but he needs to be by November in order to protect him from the Rule 5 draft, so it wouldn't be surprising to see the Sox move up that timeline by a couple of months in order to get his feet wet after a highly successful campaign in the minors as a 20-year-old.

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Like with Bradley, Bogaerts would be unlikely to take on a regular role, but could get his spots here and there to contribute, or at least to see some real, live, major-league arms on the mound. The real goal would be acclimating him to the big-league culture that he might from that point be a part of: Bogaerts could very well be Boston's starting shortstop in 2014, from Opening Day onward.

Alex Hassan

It's been a successful last year for Hassan, who was added to the 40-man to protect him from the Rule 5 last November, and has justified that decision despite missing the early part of 2013 with a broken foot. He's hit .307/.419/.455 in 51 games with Triple-A Pawtucket, and has spent time in both corner outfield spots as well as first base while doing so.

The Sox already have players who can do that in the majors, which will likely limit any time Hassan spends on the field in September. There's little point in sending him home after the minor-league season ends, though, so he too should get his first taste of big-league action, as brief as it might be, when rosters expand.

Dan Butler

Backstop Ryan Lavarnway is in his last days as the backup catcher in Boston, assuming David Ross' rehab continues to go smoothly. The Red Sox have made a point of using Lavarnway sparingly while he's filled in for Ross, as he's caught all of 12 of 45 games during that stretch, with Jarrod Saltalmacchia assuming the rest of the workload.

That might be where Butler comes in. While Lavarnway has played sparingly with the Sox, Butler has been the starting catcher for the PawSox, and is now hitting .270/.365/.489 on the season with superior defensive skills to Lavarnway. He's picked it up as the season has gone on, too, with a 1205 OPS since the Triple-A All-Star break, suggesting he's maybe figured out International League pitching and is ready for the next test. It's no guarantee, but Butler might have played himself into the September third catcher role with his performance over the last couple of months. The Red Sox had enough faith in his future and potential value to add him to the 40-man roster last November, and he's exceeded any expectations that were in place since that time.

It will be interesting to see which of the two is the starter in Pawtucket once Lavarnway is sent back down for Ross' return.

The Relievers

Why Will Middlebrooks over Xander Bogaerts makes sense

Will Middlebrooks was called up from Pawtucket on Saturday despite Xander Bogaerts knocking on the door. This move makes sense for this year's team, as well as next year's.

If they are a reliever on the Red Sox 40-man, they will very likely be in Boston once Pawtucket's season is over. Pedro Beato, Jose De La Torre, Alex Wilson, and Steven Wright all have spent time with the Red Sox at various points in 2013, and all will surely join the big-league bullpen for any opportunities to lighten the workload of the regulars. Then there is Brayan Villarreal, acquired from the Tigers in the three-team Jake Peavy trade. He has a live arm, and while he's had some issues in the past, he's not the first reliever the Sox have brought in under similar circumstances. Andrew Miller, Clayton Mortensen, Franklin Morales, and the aforementioned Beato all fit under that umbrella, and have had varying degrees of success.

Then there are pitchers who, if there is room on the 40-man roster, could be added, like Chris Martin, Ryan Rowland-Smith, or even starting pitcher prospect Anthony Ranaudo. These are less likely additions, simply because the 40-man roster is already packed and there are only so many places to make space, especially if the expectation is that Bogaerts will arrive. It might not be necessary anyway, though, considering that five arms from the preceding paragraph should be quite enough in a month with four scheduled off days.

Read more Red Sox:

• Give me more Jonny Gomes
• The transformation of Red Sox prospect Alex Hassan
• On Daniel Nava and baseball players as people
• Red Sox system loaded with pitching prospects, from top to bottom
• It's time to bring Xander Bogaerts up to the Red Sox