If you were listening intently -- or even only half-listening -- to the KRLD-FM radio broadcast after Delmon Young jacked a poorly located Cliff Lee change-up early in last night's game, you probably detected the slightest twinge of annoyance in Eric Nadel's voice as he explained Lee's recent usage pattern. When Lee hasn't been dominant, it has seemed as though there's always been some sort of extenuating circumstance making his performance appear to be worse than it actually was (e.g. porous defense, bullpen problems), and now with no such reasons available to exonerate Lee from last night's effort, there's a building crusade of sorts against his every-fourth-day pitching schedule.
Most of Lee's recent problems appear to stem from flagging command, a symptom often ascribable to pitcher fatigue; however, Lee insists he is neither fatigued nor in need of an additional day of rest, so that should be the end of the story, right? Not necessarily. I'm absolutely not going to accuse Lee of outright prevarication, but there's a key distinction to be made between Lee refuting talk of him being a lock to sign with the Yankees -- talk which doesn't even matter, because he's almost certainly going to the highest bidder no matter what -- and Lee attempting to preserve the image of being an ultra-durable ace who can shoulder any innings-based workload so long as he receives his standard four days of rest between starts. He has a deeply vested interest in maintaining such an image.
What none of this answers is the question of whether working in a few extra days of rest for Lee now will pay dividends later. Intuitively, you would assume the answer to be 'yes,' and anecdotally, this proved the case last year when the Phillies granted him one extra day of rest after a bad three-start run near the beginning of September, but a couple of problems surface here: (a) Lee actually received five days of rest before the second of those three consecutive poor starts, a game in which he allowed six earned runs in just three innings, and (b) if the extra day of rest truly did produce some performance-boosting effects, they were short-lived, because he got hammered in his final two regular-season starts of 2009. Not an especially strong anecdotal example.
What about on a more holistic level? For his career, Lee is materially better when pitching on five days' rest (1,822 PA, 3.64 FIP, 3.55 K/BB) than on four days' rest (3,197 PA, 3.80 FIP, 2.88 K/BB), a deviation large enough that I'm a bit inclined to believe it's not just a fluke ... but at the recent SABR 40 convention, Baseball Reference founder Sean Forman and baseball economist J.C. Bradbury found that the impact of days of rest on a starting pitcher's performance is negligible to the point of not being statistically significant. In other words, the population as a whole performed essentially the same regardless of the number of days of rest. I'm still more inclined to believe that Lee's a little better on extra rest than the study's findings might have you believe, but I don't think it's definitive either way.
With the Rangers still miles ahead of the second-best team in the division and home-field advantage not being an utterly dire need, I guess there's no real harm to be inflicted by throwing a few extra days of rest here and there at Lee. If he's not fatigued, you lose only a start or two at most in the process (and probably don't lose any real ground in the division race), and if he's more fatigued than he's letting on, well, then maybe it pays off later ... but that's a very strong "maybe." It will make for a very neat and tidy narrative if Lee receives extra rest and pitches well immediately thereafter, but if that happens, the rest likely won't have been as instrumental as you'll have been led to believe.