The St. Louis Cardinals should stay away from a six-man rotation

Coming off of a 58-game season and no minor leagues in 2020, should the St. Louis Cardinals go to a six-man rotation?

Planning the rotation for 2021 isn’t going to be easy for the St. Louis Cardinals. There are a number of dilemmas for Mike Shildt to work through in Spring Training including:

  • No Dakota Hudson due to season-ending surgery after the 2020 season
  • Miles Mikolas returning from surgery after sitting out the entirety of last year
  • Adam Wainwright pitching in his age 39 season
  • Jack Flaherty coming off of a down year, by his high standards
  • Carlos Martinez being the continual unknown quantity he has been in recent year
  • Kwang Hyun Kim pitching in just his second season and first full 162-game season in the majors

With all of this in mind, there is the ever-present challenge of pitchers coming off of a disjointed 2021. There was very little consistency of days rest between starts, a jumbled rotation with players coming on and off of the COVID-list, and finally no minor league for the younger stars.

This has created a very valid point around pitcher health in 2021 and ensuring that pitchers can complete a full season, healthy and without major injury.

There has been a lot of media buzz around whether a good way to deal with pitchers not being ready for the extent of a 162 game season is via a six-man rotation. This would allow additional rest between starts for pitchers and if this means better pitcher health, it is certainly something that would be very appealing for the Cards.

Six-man rotations have been discussed and used in part by other teams historically, for example, the Seattle Mariners dabbled with this in 2020. There is, though, no scientific evidence of whether it makes a significant impact on pitcher health and therefore whether or not it is worthwhile.

What does this look like in reality?

In a five-man rotation, a typical pitcher would average 192 innings of work a season. If the Cardinals were to include a sixth pitcher in the rotation, this reduces each pitcher’s workload to roughly 162 innings which shows the obvious benefit after a shortened year.

The first big question raised here is if the St. Louis Cardinals really want to remove 30 innings of potentially Cy Young quality pitching from Jack Flaherty and replace it with 30 innings from the likes of Daniel Ponce de Leon or another young arm?

ST LOUIS, MO – SEPTEMBER 08: Daniel Ponce De Leon #62 of the St. Louis Cardinals reacts after giving up a two-run home run against the Minnesota Twins in the second inning during game two of a doubleheader at Busch Stadium on September 9, 2020 in St Louis, Missouri. (Photo by Dilip Vishwanat/Getty Images)

Considering Ponce has a career 4.76 xFIP when starting in the majors, that may not be the best idea if the Cards are looking to win the Central.

If I, very crudely, compare Ponce De Leon’s career 4.17 ERA as a starter to Flahertys career 3.38 starting ERA, we see a 0.79 difference in ERA. Now if we extend this over these 30 innings, that is the potential for roughly 13 extra runs allowed – not ideal!

In order to create these 30 fewer innings per pitcher, this increases the number of days between starts. Looking at the Cardinals’ top pitchers, they have historically performed better when pitching after a “standard” 4-5 days rest as opposed to any more than this.

Taking the career lines of Flaherty, Waino, Mikolas, and Martinez we see that on a “standard” 4-5 days rest, they have 3.44 ERAs. Whereas when pitching on 6+ days rest, this number jumps up to a 3.62 ERA which again increases the number of additional potential runs allowed.

Finally, if the team were to run with the six-man rotation, that is an additional roster spot required for that sixth starter. This meaning the Cards would either have to go in with a:

  • Reduced bullpen with one fewer piece – this isn’t ideal over a 162 game season when a strong bullpen can really drive a team through the long grind of the season
  • Man down on the bench – this likewise isn’t the ideal situation for the St. Louis Cardinals who are going into 2021 with question marks over the outfield. Being able to carry that depth of outfield rotation could be pivotal for the Redbirds during the season.
What could the six-man rotation look like for the St. Louis Cardinals?

All-in-all, there isn’t much evidence that a six-man rotation would be that beneficial for the Cards. Throwing fewer pitchers from your ace and replacing those by a far less strong candidate. Removing a bullpen piece/bench player for the season to add an additional day’s rest doesn’t appear to be a net-positive.

Everything says to stick with the standard five-man rotation and all the challenges that come along with this.

JUPITER, FL – FEBRUARY 28: Teammates look on as Miles Mikolas #39 of the St Louis Cardinals warms up in the bullpen prior to the spring training game against the New York Mets at Roger Dean Chevrolet Stadium on February 28, 2019 in Jupiter, Florida. (Photo by Joel Auerbach/Getty Images)

Just for fun though, since the Redbirds have a number of quality starting pitchers in my mind the rotation would look something along the lines of:

  1. Jack Flaherty
  2. Adam Wainwright
  3. Kwang-Hyun Kim
  4. Miles Mikolas
  5. Johan Oviedo
  6. Alex Reyes / Carlos Martinez / Daniel Ponce De Leon / John Gant

Having not even started Spring Training yet, there is a lot of time for a breakout star to cement their place in the rotation. Or, a lot of time for a rotation mainstay to drop a bombshell and create even more questions.

Time will only tell on this one, but more will be revealed about the quality of the rotation throughout March!