Back on November 2, Yankees pitching coach Larry Rothschild appeared on SiriusXM and indicated that Andy Pettitte's family was comfortable with not having him underfoot next year. He also dropped a tantalizing hint about the geriatric starter's potential workload.
On board with him returning, most likely returning but keep him below 30 starts. On Kuroda- if pitching in US, high % he returns to NYY— Jim Duquette (@Jim_Duquette) November 2, 2012
Think of Pettitte as "Sunday Starter Andy." Back when baseball had scheduled doubleheaders, they often needed an extra starter to avoid disrupting their rotations. This role was usually filled by the now largely extinct "swing man," the quagga-like half-starter, half-reliever (the swing man, specimens of which can be observed in the American Museum of Natural History in New York, were extinct in the wild as of the late 1980s, out-competed by situational lefties which devoured their life-sustaining roster spots; a few survived in captivity, but the last died in 1991 without successfully reproducing), but sometimes there was a dedicated starter purely for this purpose.
The most famous exemplar of the Sunday starter was future Hall of Famer Ted Lyons; the White Sox used the aging righty in the Sunday starter role for several years at the end of his career. In 1942, this led to one of my favorite seasonal lines of all time: Lyons, then 41, made 20 starts, completed all 20, and led the American League with a 2.10 ERA in 180.1 innings. Perhaps Pettitte has a similarly strong season left in his 41-year-old arm. If he does, that would help make up for one of the problems created by restricting a starter's workload -- it pushes starts/innings off on other pitchers, most likely inferior ones.
Let's not be too hasty, though. Those pitchers might not be inferior. That is, they will be inferior to vintage Pettitte, but there is no guarantee that Pettitte will be able to bring the same stuff at 41 as he has in prior years. It seems likely given how well he has pitched when he has been able to take the mound (two strong post-season starts included) that he should be able to, but of course one of baseball's enduring difficulties is trying to figure out when a player is going to lose it. If you have a pitcher who is in his 40s and still playing, he's already in sudden-death overtime. For all the progress we have made in analyzing baseball since the dawn of Bill James, there is still no good way to predict when a player will hit that final wall. The best we can do is look at comparisons and say the older a guy is and the more complex his injury history, the more likely it is to happen now. Pettitte is well into that red zone.
Pettitte's June leg fracture was a fluke, but his injury history is like a great salad bar, with relatively few stints on the disabled list but every form of day-to-day known to man except "bitten by unknown marsupial."
Just as a point of comparison, pitchers born the same year as Pettitte include Brad Radke, Mike Hampton, Jose Lima, Darren Dreifort, Salomon Torres, Ramiro Mendoza, Armando Benitez, and Keith Foulke. Some of these guys have been gone for what seems like lifetimes. Pettitte is living on borrowed time.
Lefties usually don't last forever. Since World War II, there have been only 14 seasons in which a left-handed pitcher 41 or older pitched 190 innings in a season. The list basically boils down to Warren Spahn, Randy Johnson, Jamie Moyer, and five other guys who did it once each. Spahn was excellent through his age-42 season, winning 23 games that year. The Yankees got a 3.79 ERA from Randy Johnson and 211 strikeouts when the Big Unit was 41; he posted his lowest strikeout rate in 15 years, but historically speaking it's a great season by the standards of the age group. David Wells was a league-average pitcher for the Padres when he was 41 and had another half-decent season the next year. Moyer obviously made a go of it for years after his 41st birthday.
The problem is, you can't really extrapolate from these cases (the three pitchers I haven't mentioned: Kenny Rogers, Tom Glavine, and Jerry Koosman). By their very nature, they are outliers, not just in that they are among the handful of southpaws that lasted that long, but also to begin with. There is no pitcher in baseball history truly like Randy Johnson. I hesitate to compare David Wells to anyone.
Since the Yankees would try to limit Pettitte's starts, we can drop our threshold down to 150 innings. That really doesn't change anything; it brings more Wells, Johnson, and Spahn seasons and adds Tommy John, another unusual pitcher, to the mix. Almost all of the added seasons are exceedingly poor.
Pettitte's immediate future, then, is anyone's guess. You can hear a clock ticking somewhere, but since you can't see it, you can't know how close it is to chiming.