PORTLAND — Clay Buchholz signed a contract this past week that makes him a Boston Red Sox pitcher through at least 2015 and likely through 2017.

There goes another vacancy on the major league team.

As general manager Theo Epstein locks up young players to long-term contracts, the chances for players in the Red Sox farm system become fewer.

Think about it. If you’re a starting pitcher, what are your chances of cracking the Boston rotation? John Lackey is signed through 2015, Josh Beckett through 2014 and Jon Lester through 2013 with a club option for 2014.

Daisuke Matsuzaka’s contract ends after next season. That leaves one opening and if you believe Terry Francona’s gushing over Felix Doubront, that position already has “a strong internal candidate.”

What’s a pitching prospect like Stolmy Pimentel to do?

Answer: Shrug.

Pimentel, 21, the highest-rated pitching prospect on the Portland Sea Dogs, and the only Portland pitcher on the 40-man roster, didn’t even know about Buchholz’s new contract the day after he signed it.

He wasn’t bothered by it.

“I’m not scared,” he said. “It’s like everybody says: We’re not only playing for the Boston Red Sox. We’re playing for all the teams.”

In other words, you can’t worry about players in front of you. Just play well. Not only is your manager watching, but so are scouts from the other teams.

It’s probably good advice for others, including former Sea Dogs first baseman Lars Anderson. Now in Pawtucket, Anderson’s path to the majors is blocked by Adrian Gonzalez who just signed a seven-year contract extension.

Other positions that will have a no vacancy sign, assuming there are no injuries, are left field (Carl Crawford signed through 2017) and second base (Dustin Pedroia, 2015).

Third baseman Kevin Youkilis is signed through next year with an option for 2013, when he’ll be 34.
Center fielder Jacoby Ellsbury becomes a free agent after the 2013 season and with Scott Boras as his agent, likely will test the market.

Shortstop Marco Scutaro has an option for next year and right fielder J.D. Drew’s contract is up after this season.

The catching is unclear. Jason Varitek, 39, is on yearly contracts. Jarrod Saltalamacchia, who becomes a free agent after 2013, is still trying to prove himself.

So where does that leave the minor leaguers?

Strong internal candidates remain for the outfield (Ryan Kalish) and shortstop (Jose Iglesias, although Jed Lowrie may have something to say about that).

Third baseman Will Middlebrooks, 23, has impressed in his first week in Portland, batting .407 through Thursday with a 1.243 OPS (on-base plus slugging percentage), a quick glove and a cannon arm. But it’s a small sample.

And the catching tryouts continue. Dusty Brown has moved on to the Pirates’ organization. Mark Wagner was taken off the 40-man roster and is now the third catcher in Pawtucket.

Newly acquired Michael McKenry and former Sea Dogs catcher Luis Exposito get a chance to prove their worth in Triple-A. Portland may have the best prospects in Tim Federowicz and Ryan Lavarnway.
Starting positions are rare in Boston. But they will open up here and there in the next few years. Maybe even a starting pitcher will make it.

“Anything can happen,” Pimentel said.

• In the Sea Dogs’ season-opening homestand, a few things were learned, besides the fact that Middlebrooks shows himself to be a legitimate prospect.

Right-hander Alex Wilson keeps demonstrating why he might be the first player promoted out of Portland (2.45 ERA, 0.82 WHIP).

If he keeps his fastball command — one walk in two starts — and controls his power slider, Wilson appears to be prime bullpen material should the need arise.

Also on the impressive list is left fielder Alex Hassan. His numbers were solid in Salem last year but he looks even better in Double-A. He isn’t overmatched with a .500 average and .563 on-base percentage.

• The Sea Dogs’ next homestand runs from Thursday through April 28 with a day off for Easter. Among the highlights are fireworks after Friday’s game, and a Jon Lester bobblehead giveaway on April 27.