For obvious reasons, most of the offseason Red Sox chatter has focused on free agents. From Mike Napoli to Zach Greinke, the allure of the shiny baubles on the open market has proven too much to ignore. Which is expected, but misguided. As the front office has said on more than one occasion, the best improvement the 2013 club can make it by getting more out of their existing roster.

When Cherington says that, he is primarily talking about pitchers like Buchholz or Lester who substantially underperformed expectations last season. But it will be nearly as important to extract value from further down the roster; one of the real failings of the Red Sox front office the past few years has been in our depth, or lackthereof.

On that note, here’s a look at two players who are criminally underdiscussed this offseason. For better, and we hope not, for worse.

Rubby De La Rosa

Here’s Keith Law on Rubby de la Rosa following the Dodgers / Red Sox trade:

Rubby de la Rosa blew up as a prospect before blowing out entirely back in 2011, but he’s back from Tommy John surgery and, by 2013, should be able to pick up where he left off when his elbow snapped. He has touched 100 mph as a starter and sits comfortably in the mid-to-upper 90s, offsetting it with an above-average changeup with good fading action in the mid-80s, and, before the surgery, could throw both pitches for strikes. His slider is hard but really short, 82-86, but it doesn’t have a lot of tilt to it because he tends to get on top of the pitch, often coming out higher than he does on his fastball; his curveball, a pitch he seldom throws, is in the mid-70s, breaking down but without tight rotation.

Even an average slider would give him No. 1 or No. 2 starter potential, and I think he can get there if he can release it from a slightly lower spot, closer to where he releases the fastball. It’s a huge arm in any role, and, as long as he’s healthy, he should be able to start.

In spite of the glowing reviews, however, de la Rosa’s name is rarely if ever mentioned as a realistic rotation candidate this season. Career, de la Rosa’s struck out 8.8 per nine, a good if not overwhelming number, although he’s walked too many over that same span (4.84). In 2010 with the Dodgers Single A affiliate, he struck out 55 in 59.1 IP; in 2011 with the Dodgers, it was 60 in 60.2 IP. He’s not yet 24, he’s demonstrated the ability to miss bats, he shows no major platoon splits (< .100 OPS difference L vs R), he maintains his velocity, and with the player a full season removed from Tommy John surgery, de la Rosa should at least be in the conversation for a back end starting role, his control issues notwithstanding.

Will Middlebrooks

As much as it’s a surprise that de la Rosa’s abilities remain off the radar, the lack of concern about Middlebrooks’ plate discipline is even more perplexing. People seem to be taking it for granted, on the basis of a few hundred at bats, that Middlebrooks is a middle of the lineup fixture for years to come. The problem is that the data is much less conclusive on that subject.

Granted, he tore up the minors last year (.333/.380/.677), and his partial season line (.288/.325/.509) in the majors is respectable if light on on base percentage. But after a hot start Middlebrooks cooled off significantly before breaking his wrist. The wrist injury is itself enough cause enough for concern, as such injuries tend to depress power for a season or more. But his performance prior to the injury is also problematic. Here’s his OPS by month: May (.922), June (.836), July (.785) and August (.673). His numbers also benefitted from a slightly elevated BABIP (.335). Worse, his contact issues point to a real potential problem.

Looking at MLB third basemen with a minimum of 250 at bats last season, here’s how Middlebrooks fared in contact categories:

• BB%: 40th of 45
• K%: 6th of 45
• BB/K: 44 of 45 (only Pedro Ciriaco was worse)
• OBP: 23rd of 45

In general, plate discipline is regarded as being a good predictor of future performance, and indeed is core input to many projection systems. It should come as no surprise, then, that ZIPS’ preliminary projected numbers for Middlebrooks are not promising: .255/.292/.434. For context, the average third baseman last season put up a .267/.328/.426 line. ZIPS predicts, in other words, that Middlebrooks will be a below average third baseman next season.

Best case for the Red Sox is that Middlebrooks’ power and plate coverage buys him time to improve his pitch recognition skills, and that his above average slugging percentage offsets his on base percentage. But it’s worth noting that the players that Cherington has pursued this offseason, even while shopping in the bargain aisle, have had reasonable on base skills.

It’s an acknowledgement that OBP was, for the first time in years, a weakness for the Sox, one that needed to be remedied. It may also be an acknowledgment that while Middlebrooks will be the team’s third baseman next season, he may be more likely to be part of the problem in that regard than the solution.