It appears as though Michael Pineda is coming back ahead of schedule. Brian Cashman previously said not to expect Pineda to pitch another game in August and that he would return at some point in September. As it stands though, it looks like the recovery from his forearm strain might have gone a little better than anticipated.
Girardi said Pineda is expected to start on Wed vs Astros. That moves Tanaka back to Friday.— Jack Curry (@JackCurryYES) August 22, 2015
As of right now, Girardi said Yankees will go with a 6-man rotation.— Jack Curry (@JackCurryYES) August 22, 2015
This makes a lot of sense with the lack of off-days the rest of the way and September roster expansions are just around the corner, so the team won't be short-staffed in the bullpen for long. The Yankees will hopefully soon have six healthy starters, and with the injury concerns over a few of them, they'll look to do everything possible to keep it that way for the last few weeks of the season.
As it stands, though, all six starters would be expected to return next year. Things could certainly change in the offseason, and the Yankees could always look to add another starter to the ranks as well, so nothing is set quite yet. But would the Yankees consider going forward with a six-man rotation in 2016 on a more frequent basis?
The team has looked to get Masahiro Tanaka an extra day of rest wherever possible, motivated by the elbow but perhaps also partially driven by a desire to keep him on a schedule more akin to what he had pitching in Japan. CC Sabathia has performed better in recent weeks as the Yankees have used off-days and the occasional Bryan Mitchell start to give pitchers an extra day off. Perhaps correlation does not necessarily imply causation there, but the possibility of an extra day helping Sabathia out as well is something Joe Girardi has acknowledged. For these two pitchers in particular, the reasons to remain on five days rest will carry into next season.
If healthy, Pineda and Luis Severino will hopefully be stretched out for fuller workloads next year, and Nathan Eovaldi is effectively the resident workhorse of the staff, or would be as long as his pitch counts allow him to reliably work deeper into games. Ivan Nova might be the most likely of the six to have innings limitations as it'll be his first full season coming off Tommy John surgery. If Severino can continue pitching the way he has over his first four starts, even as hitters adjust to him, he'll be difficult to send back down at the start of next year.
Sabathia is effectively signed through 2017–unless he ends 2016 on the DL with a left shoulder injury–so he'll likely start out in the rotation barring a true collapse this September. Perhaps then Nova is most replaceable, but without options, would they demote him to the bullpen? Should the Yankees go out and add a Johnny Cueto or David Price, they will want their prized asset making 30+ starts, but barring that, distributing innings and keeping their rotation depth stretched out and contributing might be worth considering. Especially if it allows Joe Girardi to ride out an effective starter a little longer in each game.
At the very least, it looks like the Yankees will close out the season with a six-man staff, and the other New York team might well do the same. Other teams around the league may consider working in a sixth starter, including the Rockies and perhaps the Indians as well. It's possible that we're in the relatively early stages of an MLB-wide shift to regular five days rest between starts. Going off the way the shift from four to five-men rotations took place, it might well be years, perhaps decades, if this ever does happen. The shift is widely acknowledged to have taken place for good in the mid-1970's, but regularly starting five men on four days rest can be traced back to Joe McCarthy's 1928 Chicago Cubs. Over the next five decades, MLB teams saw the balance of rest days between starts fluctuate, but trend upwards, until the four-man staff started falling out of favor from about 1975.
Similarly, we might see some teams take the lead on six-man rotations in the coming years, finding a way to make it work with present roster constructions. There has been some research to suggest it might help with injury rates in some situations, but perhaps more conclusive results will come with more data if teams such as the Mets continue to use it in the coming years. If ownership groups come on-board with these ideas to protect their investments, they would likely have the support of the unions to add a 26th man to the roster, as Eno Sarris points out here. This is all still a ways away of course, but if this happens, and if the data supports the idea of less frequent injuries, more teams might push forward with expanded rotations.
First there will need to be a few teams that will find this strategy as a necessity in order to get the ball rolling on a significant shift in the way pitching staffs will be arranged in the 21st century. Perhaps the Yankees, not always known as organizational experimenters, might even be among the early adopters. Perhaps as early as this and next season.