With the July 31 trade deadline coming up, what will the Boston Red Sox do?

They head into the All-Star break in first place in the American League East. The Red Sox can try to improve their team, and they have prospects galore to trade if they want.

But why would they want to?

The Sox prospects that have proven their worth at Hadlock Field in Portland and McCoy Stadium in Pawtucket are the future at Fenway, and that’s not just a marketing slogan for the minor league teams.

Jackie Bradley Jr., Xander Bogaerts, Brandon Workman, Anthony Ranaudo, Garin Cecchini These are players who will bolster Boston in future years, and both Bradley and Workman are helping out right now.

Surely not every prospect being groomed by the Red Sox will make it. General Manager Ben Cherington is making his list of untouchables and “tradeables.” Brand new Sea Dogs outfielder Brandon Jacobs was in the latter category, having been sent Friday to the Chicago White Sox for left-handed reliever Matt Thornton.

When making that list, Cherington will look at what the Red Sox look like now and what will they look like in the future. Among the factors are contracts and when players will become free agents (eligibility begins after six seasons).

Here is what we see, position by position:

STARTING PITCHERS

This vital position is a strength for Boston. Allen Webster, Rubby De la Rosa, Steven Wright and Workman have already appeared in the majors. Drake Britton just reached Pawtucket. Ranaudo and Matt Barnes are in Portland, and Henry Owens could be there at the end of the year.

Having so many arms gives Boston depth to cover injuries (Clay Buchholz), as well as opportunities to fill bullpen roles.

Boston would not hastily trade away a quality arm, given the cost of pitchers on the free-agent market (Ryan Dempster, a No. 4 starter, signed a two-year, $26.5 million deal with Boston).

RELIEF PITCHERS

No place features more turnover than the bullpen. Piecing together an effective group of relievers may be any GM’s biggest challenge. Boston has already lost closer Joel Hanrahan and Andrew Miller to injury (and Hanrahan is a free agent after this season).

This is one area where Boston may make another trade to improve although, as already mentioned, there are bullpen possibilities among Boston’s starting prospects.

Alex Wilson has proven he can contribute. Jose De La Torre has been called up to help sometimes. Daniel Bard remains a mystery as he tries to rebound from his command troubles. Chris Martin and Brock Huntzinger are coming on in Pawtucket. Chris Hernandez and Will Latimer are lefties in Triple-A but not yet ready.

CATCHER

Jarrod Saltalamacchia strikes out a lot (95 times through Friday), but he also is batting a respectable .269 with eight home runs.

There has not been much chatter about Saltalamacchia’s thoughts on his future. If he and Boston part ways, the Red Sox still look solid. David Ross, who is recovering from a concussion this year, can mentor Ryan Lavarnway next season. Both are better defensively than Saltalamacchia, and Christian Vazquez appears to be the best of the bunch behind the plate. Blake Swihart, 21, is developing in Class A Salem.

Dan Butler gives Boston insurance if it needs a solid backup.

INFIELD

It’s hard to predict this position with so much young talent. Who figured that Jose Iglesias would take Will Middlebrooks’ job at third base? And when Iglesias is filling in for Stephen Drew at short, Middlebrooks has stayed in Pawtucket, with Brock Holt manning third.

Middlebrooks, however, still has a future with Boston. It might be at first base, especially with Iglesias at shortstop and the Red Sox needing to find a way for Bogaerts to break into the lineup.

But third base has another candidate for the future, with Cecchini tearing up Double-A pitching(.385 through 18 games). And Deven Marrero, in Salem in his first full pro season, may challenge at shortstop. Holt seems like a valuable utility player, while there may be no room for Michael Almanzar.

OUTFIELD

Jacoby Ellsbury is looking for a big free-agent payday, which means Bradley may become the regular center fielder in 2014. There are no other sure bets among the prospects. Bryce Brentz is a streaky power hitter who is on the disabled list because of a sore knee. Alex Hassan has also been playing first base and may someday fill Mike Carp’s versatile role. Ryan Kalish was once on the fast track but has spent too much time on the DL.

DESIGNATED HITTER

Who knew David Ortiz would be so productive at age 37? But when his contract is up, would Boston gamble on a 39-year-old slugger in 2015? More likely, Boston will have a more versatile lineup after 2014, with different players filling in at DH, which may help keep Bogaerts, Cecchini and Middlebrooks in the lineup together.

BOSTON APPEARS to have a solid plan. Don’t expect Cherington to deal any of the sure-bet prospects.

But he will trade excess, even if it looks like a small deal. When it became apparent that first baseman Lars Anderson did not fit into Boston’s plans, he was dealt to Cleveland last year. In return the Red Sox received Wright, the knuckleballer who was Boston’s winning pitcher Thursday night.

Fans in Portland have seen Boston trade prime prospects before, like Justin Masterson and Anthony Rizzo. And they have seen Boston groom others for a future at Fenway (Ellsbury, Dustin Pedroia, Jon Lester, Buchholz, etc.).

As Boston gears for a drive to the playoffs this year, we will see who they hold onto for later.

Kevin Thomas can be reached at 791-6411 or:

kthomas@pressherald.com

Twitter: @ClearTheBases