Which starter could the Red Sox trade this offseason?

After a last-place finish and a front-office shakeup, the Red Sox enter the offseason with a clear goal in mind: to upgrade a pitching staff that all too often prohibited success for Boston in 2015.

Speaking to the media last week, Dave Dombrowski acknowledged that his foremost objectives for this winter would be to rebuild a beleaguered bullpen and add a "horse" to lead the club's rotation. For the second straight offseason, then, Red Sox fans will be following the rumor mill in hopes the front office can find the type of frontline pitcher the team has lacked since trading away Jon Lester in 2014.

While Dombrowski discussed Boston's need to upgrade its pitching staff, he also spoke about the depth the squad already has in the rotation. Indeed, despite all the scrutiny surrounding their pitching woes, the Red Sox ended the year with a group of starters that consistently gave them a chance to win on a nightly basis. A staff that posted an AL-worst 4.75 ERA during the season's first half improved that mark to an above-average 3.97 after the All-Star Break.

With Wade Miley, Rick Porcello, and Eduardo Rodriguez all slated to factor into the rotation picture, and Clay Buchholz set to return from injury, the Red Sox already have four starters for 2016. That group doesn't include Henry Owens, who made a compelling case to begin next year in the majors with his performance down the stretch. Joe Kelly, too, is another candidate for the rotation, even if there remains a strong possibility he ends up in the bullpen.

Although Boston will be looking to add a top arm this offseason, they already have their fair share of starting pitchers. For this reason, could Dombrowski end up trading from what is, oddly enough, a position of strength depth-wise for the Red Sox? And if, moreover, Dombrowski decides to deal for an ace rather than spend big money on a hurler on the open market, could one of the club's current starters be included in a potential trade?

The thought of the Red Sox trading away a starter this winter sounds strange at first, but the team will need to make some room for another pitcher on its starting staff anyhow.

Which of Boston's current starters, then, could be sent elsewhere this offseason? Here are the four most likely candidates:

Wade Miley

Miley's first year in Boston was a bit strange, with the lefty swapping impressive outings with mediocre ones on a weekly basis. Overall, though, Miley gave the Red Sox just what they hoped for—nearly 200 innings of slightly above-average pitching for minimal cost.

What makes Miley so valuable in Boston (his solid track record of health and team-friendly contract) is exactly what could make him an intriguing trade chip, of course. Miley alone won't fetch a frontline starter, but combined with a few of the organization's best prospects, he could prove to be a solid deal sweetener. With two years and just over $15 million remaining on his current deal (plus a team option for 2018), Miley won't represent a financial burden to any opposing club either.

Clay Buchholz

Assuming the Red Sox pick up Buchholz's option for 2016 (and all signs point to them doing so), he'll have just one year remaining before he enters free agency next offseason, which makes him far easier to move via trade. His injury issues aside, Buchholz proved he can still dominate big league hitters in 2015, posting a 22.8% strikeout rate, 4.9% walk rate and 2.68 FIP over 113.1 innings pitched.

Still, given his season-ending injury, the Red Sox won't have much leverage until Buchholz proves he's healthy, which makes a potential trade this winter difficult. Considering his upside, Buchholz might have more value to the Red Sox than anyone else with all the questions surrounding his right arm.

Eduardo Rodriguez

It's hard imagining the Red Sox trading away Rodriguez, who flashed front-of-the-rotation potential himself during an impressive rookie campaign. But with Dombrowski in charge, there's no telling what kind of trade the Red Sox will make this offseason.

And if Boston is going to part with Rodriguez, you can bet a big name will be coming back in return. Expecting Dombrowski to land someone like Sonny Gray, Matt Harvey or Chris Sale is ill-advised, but that's the type of return a package involving Rodriguez could garner.

Henry Owens

There's a lot to like about Owens. He turned just 23 in July, and he possesses a four-pitch arsenal that garnered loads of swings and misses during his MLB debut in 2015. Yet questions remain about just how high his ceiling is. His command issues still need to be rectified, and when he's not locating it down in the zone, his fastball can be very hittable.

Owens certainly holds plenty of promise, and young, cost-controlled pitchers are the most valuable commodity in baseball. But if the Red Sox have the choice of holding onto one of their rookie lefties, Rodriguez is the clear pick. One wonders just how much Owens could bring back in a trade, especially after a solid first few months in the big leagues.

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There remains a chance the Red Sox don't trade any of their starters this winter, and instead sign one of the prized free-agent pitchers to a big deal. Ownership's reluctance to commit big money to an aging arm in the past means a trade is a realistic possibility, however.

While Porcello struggled for much of 2015, his contract makes him far harder to move than any of the names above. Given Buchholz's health status and the high regard in which the organization holds Rodriguez, Miley and Owens appear to be the two most likely to be traded if Dombrowski decides to deal away a starter this offseason.