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Looking inside 6-man rotation options - Part 1

What if we just tried protecting Ohtani’s 5 days of rest?

Shohei Ohtani Farewell Ceremony Photo by Masterpress/Getty Images

A 6-man rotation is a major departure from the Baseball status quo. Baseball is a game of traditions over the years. And it is also a game of dependable cycles and patterns upon which players come to expect as the summer drones on. Pitchers can be sensitive beasts who insist on predictable cycles of work between outings. To mess with that takes a confident Front Office that knows how to communicate well with players, a manager who is both a strong leader and a person who knows how to be flexible and work with his players rather than against them, and players who are open-minded enough to work within the system towards a greater good. With the acquisition of Shohei Ohtani, we are going to learn just how well the Angels work together at all three levels.

What we know is that MLB starting pitchers have career paths well worn with 4 days of rest between starts. They are the premier global athletes at their skill, and their effectiveness at that level, and the maintenance o their health, is sustained by not messing with that. But that does not mean that they find exceptions to be absolutely intolerable.

And we also know that franchises have to dip into extra manpower once or twice a season to contend with oddities such as make-up double-headers, or unusual scheduling blips.

And, most important, we know that the still very young Ohtani knows only a 5 day rest period between starts.

So how do the Angels deal with the need to navigate these two differing player needs? The difference of one day may seem slight to us, but to players at the MLB level it is a big enough deal that it has driven the Eppler Front Office to work through a lot of permutations to figure this out.

I have three possibilities: stick to the traditional 5-man rotation and force Ohtani to deal with it...Install a straight 6-man rotation and force the rest of the LAA staff to deal with it...or install a flex system that changes the number of days rest between starts. It’s the flex schedule option that I am looking at first.

The goal of the flex schedule would be to protect Ohtani’s need for no less than a 5-day rest, and then flex the rest of the staff as needed on 4/5/6 day rest depending on the calendar, trying very hard to give as much predictable stability as possible. A flex schedule is the most radical of all options, since it minimizes predictability. Pitchers would not have a regular cadence. Of course, because of off days on the calendar, the reality is that there is some irregularity regardless of plans. We will see later just how radical a flex schedule is compared to straight 5-man and straight 6-man rotations when we have to deal with off days.

So what did I do? For this option I ran the schedule from Opening Day all the way out to the All-Star Break. That is enough games to get a feel for what is going on, without having to predict all the possible permutations as to what the ASG might have on available pitchers and pitching order coming out of the Break.

I walked the schedule 5 times, each time moving Ohtani from slot to slot. For the first run, Ohtani occupies the #1 slot (starting with opening Day), for the second run, he occupies the #2 slot, etc. As you will see, I don’t even bother with the #6 slot. In this flex approach, the #6 pitcher is least used, and used most randomly. I don’t really care to think about what name I would put into what other slot. I was mostly trying to guarantee that Ohtani pitch with 5 days rest as often as possible, and stretched out to 6 days rest when necessary but as infrequently as possible. the other 4 main starters work on 4/5/6 days rest as necessary, minimizing randomness. Also, I tracked the consequence of how often Ohtani would be available for DH duty, never slotting him as DH on the calendar day immediately before, or immediately after, one of his scheduled starts. This does, of course, also track the number of times that Albert Pujols would play 1B defensively.

Alright, the foundation has been laid. Lets look at the data:

The way to read this is that Ohtani fills the #1 rotation slot, ends up pitching 18 games leading into the All-Star Break, 17 of those games on 5 days rest and 1 game on 6 days rest, is available for DH duty on 48 other games, and could see 66 appearances in the first half of the season. You can also see that the days of rest is heavily weighted to 5, then 6. And all 5 of the main rotation pitchers have 18 starts in the first half.

So what you want to pay attention to is how those weights move around as Ohtani takes a different slot. Here is the result for a flex schedule with Ohtani at the #2:

You will immediately see that it is NOT the same. Of course it is not. That is because the off days on the schedule pop up at odd times which don’t fit perfectly into any plan. So we don’t want any pitcher to go to the bump on short rest, and sometimes have to wait an extra day, that wait not being applied to the same guy all the time. And we use that 6th pitcher to work around the impact of those off days to protect Ohtani. But now you can see that the 6 days of rest rises dramatically. Pitchers are flipping back and forth between 5 days of rest and 6 days of rest a lot. The traditional 4 days rest becomes rare. That might be just fine with them, I don’t know. But for strictly modeling purposes it is not ideal. Notice that we have to use that 6th pitcher a lot more. That is that random off day impact in play.

Ok, Ohtani at the #3 slot:

Not much difference from the #2 slot for Ohtani, except for dropping one DH game due to vagaries of the calendar. But I sure do like the look of the balance between each of the 5 main slots. Three pitchers have 12 games with 5 days rest and 5 games with 6 days rest, and Two pitchers are 7/3/8.

On to slot #4:

This generates the greatest number of games where the main rotation gets 5/6 days rest, mostly by cutting back on some 4 days rest games. And it gives a better balance between all 5 pitchers. They are all within 10-13 games with 5 days rest, and 4-6 games with 6 days rest. And Shohei gets 71 total appearances.

Finally , Ohtani in the 5th slot:

Here the number of games with 4 days rest rises considerably. And the flipping between days rest for the non-Ohtani slots is constant. And it’s the 2nd least number of appearances possible for Ohtani.

My conclusion is that Ohtani occupying the #4 slot, should LAA choose to go with such a flex plan, would be optimum. It puts Ohtani on the field a lot while protecting his work habits and training. It minimizes the number of times that the rest of the staff have to revert to pre-2018 regimens. And it keeps all the main rotation slots within close range of one another in terms of flex, which I would think would be easier for Mike Scioscia to manage against.

Some other points to state up front:

  • we have no basis or expecting Ohtani to occupy a rotation slot as of Opening Day,
  • we have no data yet against which we can compare for straight 5-man and 6-man rotations,
  • and that poor 6th slot is probably in for a pretty tough go of things concerning air travel.

This is NOT an exercise to tell the LAA Front Office how to run things. I am just trying to take us deeper into the reality of a 6-man rotation beyond simply stating that there is one. And if any of these end up aligning at all with what Eppler, Scioscia and team actually do, well, all the more fun.

For those curious, I can share the Excel source workbook for all this so that you can see inside the actual schedule and more of the nuance at play. Just DM me using the email address on my profile.

Working backwards, Part 2 will do the the easier thing of looking at Ohtani in all 6 slots of a straight 6-man rotation cycle, ignoring any flex. that will still be impacted by open dates, so we can compare to flex options for effectiveness.

So what do you think? Is a flex schedule a non-starter (pardon the pun)? Of those presented, do you have a different thought than mine about which one is optimum? Would you like to have the Excel doc and see if you can work it out differently?