The standard five-man rotation has been a staple of MLB teams for decades. In response to the mounting number of injuries affecting starting staffs in recent years, a few teams such as the Pirates and Braves have temporarily included an extra man on their staffs in order accommodate returning players from injuries.
Last week, Joel Sherman revealed that the Yankees are strongly considering implementing the same idea by switching to a six-man rotation once Masahiro Tanaka returns. It is also possible that this potential change in the rotation will carry over into the following season and beyond. With Michael Pineda having missed nearly three months with a muscle injury in his back, Tanaka’s rehab from his partially torn UCL, and pitchers CC Sabathia and Ivan Nova recovering from knee and elbow surgeries, respectively, the Yankees' rotation will be filled with question marks in regards to health. By switching to a schedule that would see each pitcher receive an extra day of rest, the hope is that the staff would be able to avoid significant time on the disabled list. Yu Darvish voiced his opinion about pitching with a longer rotation (I strongly recommend to those interested to read his view on it).
Despite rotations traditionally only containing five slots, very rarely do teams actually make it through an entire season with only five starters. So far this year, 210 pitchers have made at least five starts for their respective teams. Last season saw 234 pitchers make at least five starts, and 232 pitchers started at least five games for an MLB team in 2012.
During a 162-game season, adding a sixth starting pitcher would mean that each player should average twenty-seven starts. Depending on the overall situation, this could be considered both a positive and a negative. The positive is that fewer starts mean that a player should be fresher during the post-season. A season of fewer total starts also affects those still in the minors, such as Luis Severino. As a prospect that has seen a limited amount of innings despite the meteoric rise through the system, a twenty-seven start season could mean earning a spot on the Yankees' starting staff sooner than he otherwise could have. In the event of a prospect forcing themselves onto the team, there would be very little need to monitor innings workload, with the exception being if the prospect managed to come out the gate averaging seven plus innings per game.
The downside to the six-man staff would be that the Yankees would have one less roster spot available for either the bench or the bullpen. Joe Girardi may need to be more creative with how he utilizes the roster, but even this should not matter too much with players like Brendan Ryan or Esmil Rogers that rarely make an appearance in games. A six-man rotation would not be a cure-all in injury prevention, nor should it be considered one. By implementing the change, pitchers are being given more time to recover. In the long run that gives them a better chance at avoiding the major injuries that have been plaguing Major League Baseball.