I think the thing you're forgetting is that Doubront is 25 and Vazquez is 36. A 36-year-old who hasn't pitched in a year is a very dicey bet to be better than he was the last time he pitched, or even as good. A healthy 25-year-old pitcher with about 200 big-league innings under his belt, who made some progress the previous year, is a good bet to be better the following year. He may stall out at the level he's already reached, yes, but the only way you find that out is by pitching him. It's a gamble you have to take with a young pitcher as long as he continues to earn it.
Of course if you have a chance to replace him with somebody clearly and reliably better--if the choice were, say, Doubront vs. David Price or Cole Hamels--then c'est la vie. Get what you can in trade for Doubront, or throw him in the pen, and don't look back. But when the choice is Doubront vs. a guy who is unlikely to be a whole lot better, and could well be worse, I just don't see the logic of it.
It's tough to argue that Javier Vazquez (2011) wasn't substantially better than Felix Doubront (2012), especially second-half Felix Doubront. I have no qualms agreeing that Doubront's trajectory is likely upwards and Vazquez's is likely downward; however, that isn't an end-all, be-all. For example, if Doubront improves by 10% and Vazquez falls by 10% then Vazquez is still likely the better pitcher for 2013.
It's more complicated for the Red Sox because they already have a "full rotation" and pushing Vazquez into the rotation over Doubront may provide a small marginal benefit next year (let's say in fWAR), but you are also "stunting" Doubront's development and spending $X million to improve a team that might be borderline wild card contenders at best. One plus is that Doubront would be injury/suck insurance whereas right now it's questionable who that is (I'm a big fan of RDLR but others are (rightfully) skeptical that he can be an ALE starter in 2013).
I'm not advocating a serious Vazquez push unless the Sox have legitimate reasons to believe he can be a 3 WAR pitcher in the AL East (or can get him dirt cheap to play in AAA but that seems highly
unlikely). He would probably need to be sitting
in the low 90's for that to happen. However, I think people are vastly underrating how good Vazquez has been the last 6 years (many of which were in the AL) because he's a) old and b) didn't pitch last year.
For context, Vazquez is only a few months older than Ryan Dempster and has routinely put up 1-1.5 WAR more than him over the last half decade or so. And most of us agree that Dempster should provide solid value next year. Even with typical age-expected regression, though, he could still be a very good pitcher in the majors.
Edited by czar, 03 January 2013 - 12:40 PM.