Could a Shortened Season Resurrect the Four-Man Rotation?
As strange as it sounds right now, a day will come when baseball people start thinking about how to win baseball games again. That might not be until spring 2021, if COVID-19 forces Major League Baseball to sit out an entire calendar year. But there is still a chance it happens sometime in the next couple of months, and if that’s the case, teams will be preparing for a season unlike any they’ve played before. In addition to all of the structural changes that might be necessary for games to proceed, the simple fact of the season being considerably shorter than normal could change the way teams approach the games. In light of this, one strategy for teams to consider is a return to the four-man starting rotation.
Four-man rotations — or at least, the concept of throwing your best arms on three or fewer days rest — used to be fairly commonplace in the majors. In a piece by Russell A. Carleton at Baseball Prospectus from 2013, he found that around 40% of starts occurred on what we’d now call “short” rest as recently as the early 1970s. Soon after reaching that recent peak, however, the practice nosedived, with short rest starts happening less than 10% of the time by 1984 and continuing to free-fall until reaching a point of near-extinction over the last two decades.
The point of Carleton’s study was not to find out when the four-man rotation died out, but why it did. To that end, he came up with little statistical reasoning. Pitchers who threw on short rest did not seem to perform any worse than they’d be expected to on full rest, nor did any cumulative effects seem to wear them down faster over the course of a full season. This was true regardless of the time period, too, which means it didn’t seem to have anything to do with whether a pitcher was more or less conditioned for it. The best explanation for why teams broadly and swiftly shifted to a five-man rotation was simply fear of injuring arms, and hoping that more rest might prevent that.
Carleton’s piece didn’t take the extra step of actively calling for the four-man rotation to return, but plenty of others have. Major league teams, however, have been taking steps to limit the responsibilities given to starting pitchers, not expand them. In 2014, David Price led the majors with 248.1 innings pitched, while 34 pitchers reached 200 innings, and 65 reached 180. In 2019, Justin Verlander’s league-leading innings total was just 223, with 15 pitchers reaching 200 innings, and 33 pitchers reaching 180 innings. Over a full season, a four-man rotation could add as many as eight starts to a pitcher’s workload, amounting to 40-50 extra innings of work. It would be rather shocking to see a team take that kind of step over 162 games. Read the rest of this entry »