With every trading period, whether it is the offseason or late July, we hear speculation about the Red Sox prospects. Who should stay and who should go?

Last offseason, how many were willing to deal Jon Lester, Justin Masterson and Jed Lowrie for Johan Santana?

Now Lester looks like the budding ace of this staff, Masterson a key reliever, and Lowrie the future (as in real soon) shortstop.

Slowly, a blueprint appears in place for these Red Sox. Factors change, of course, especially in the injury department. But here's one consideration for the future Red Sox, position by position.

FIRST BASE: Incumbent Kevin Youkilis, 29, seems to be a Red Sox lifer (although he does become a free agent in 2011). Third baseman Mike Lowell is signed through 2010. Youkilis could switch to third after that, making room for another first baseman.

The top candidate for the future is Sea Dogs first baseman Lars Anderson, 20, a coveted draft pick out of high school in 2006 ($825,000 signing bonus). A natural and patient hitter, Anderson has a .300 average (.397 on-base percentage), with 24 home runs in 1 seasons. The Red Sox expect Anderson (6-foot-4, 210 pounds) to develop more power as he matures.

SECOND BASE: Incumbent Dustin Pedroia, 24, is not going anywhere. Free agency is not an option until 2013.

SHORTSTOP: Incumbent Julio Lugo, 32, is on the disabled list. He is expected back by September, but will he have a job? Lowrie, 24, is steadier and more dependable. Lowrie could replace Lugo the same way Jacoby Ellsbury supplanted Coco Crisp in the post-season last year.

But Lugo still has two years (and $18 million) left on his contract. Boston could eat a lot of it in a giveaway trade, or the Red Sox could bring back Lugo for one more try.

Down the road, Lowrie is not a lock for the position. Sea Dogs shortstop Argenis Diaz, 21, may be the Red Sox best fielder at any level. If he hits consistently, he's a major leaguer. Oscar Tejeda, 18, is in the mix. The Sox signed him for $525,000 out of the Dominican Republic two years ago.

THIRD BASE: Lowell, 34, is good for two more seasons. Youkilis is the likely replacement then, if Boston has another first baseman in hand.

All the scouts' eyes will focus on Michael Almanzar, 17.

It is hard to downplay a prospect when he signs a $1.5 million signing bonus at age 16.

Almanzar tore through the Gulf Coast League (.348 in 28 games) and the Red Sox surprisingly skipped him over the next level (Lowell) and he went to low Class A Greenville.

Athletic and growing (6-foot-5, 180 pounds), Almanzar could be the next Hanley Ramirez, only that Boston is likely to hold onto him.

CATCHER: Incumbent Jason Varitek, 36, is at the end of his contract, so it's a bad time to be hitting .216.

The question is if the Red Sox still want Varitek for his receiving skills and leadership? Maybe, but not for too many years.

Backup Kevin Cash, 30, is handling the knuckleball OK, and batting .235.

This position is the hardest to predict because Boston could go outside the organization for help. Pawtucket catcher Dusty Brown, who can handle a knuckleball, is having his best season (.271, 10 home runs).

Portland's Mark Wagner, 24, is considered the Red Sox best catching prospect in the system. He's batting only .244 (10 homers) in Double-A, but is coming along.

A trade or free agent signing is very possible. Or the future may be in one of the three catchers the Red Sox drafted in the top 10 rounds this year -- Ryan Lavarnway (Yale), Tim Federowicz (North Carolina) or Christian Vazquez (Puerto Rico).

OUTFIELD: Incumbents Jason Bay, 29; Jacoby Ellsbury, 24; J.D. Drew, 32; and Coco Crisp, 28 may be around for a while.

Ellsbury is another future face of the franchise. Drew has three more years...