The Orioles will finish out the home stretch of their magical season with a six-man starting rotation, moving Cole Irvin from his long relief role to their sixth starter. It is sure to come with mixed feelings, but hopefully, a deep dive in its pros and cons helps you pick a side.
Teams have played around with six-man rotations for periods of time, but never over the course of a full season. The Philadelphia Phillies are also using a six-man rotation to finish out their season.
While health is a factor in the decision to expand the quantity of starters, the bullpen picks up the added stress and less rest in the process, moving from eight arms to seven.
Today, we will debate the pros and cons of a six-man rotation and how it will affect the Orioles, both good and bad. Our RJ Diliberto will cover the pros and our Stephen Heckman the cons.
PRO:
The most obvious benefit of rolling out six starters is the extra rest it provides. Orioles starters will now get an additional one or two days off between starts.
Tyler Wells is a perfect example of the stress it can have on the body, given the substantial increase in workload. His stellar first half was followed by an 0-2 record with an ERA of 11 to begin the second half.
Dean Kremer and Kyle Bradish are also poised to shatter last year’s innings totals, so you can see clearly see the vision for why a sixth starter was added.
There is research to suggest starters are more effective when allotted the added off days. Fangraphs’ Ben Clemens looked into this and was able to find that for every additional day of rest a pitcher was given, their xFIP improved, relative to their seasonal average, by about 0.06 points. While it’s marginal and not necessarily 100% due to the rest, the data does seem to point to pitchers being slightly more effective with more time off.
CON:
While having an extra day of rest might appear to be a wise idea, you have to take into consideration where the innings go based on the innings lost.
In the grand scheme, the average starter would pitch about six innings, the first step to a quality start. Over 162 games, that comes out to about 32 starts and 192 innings in a season.
Let’s take that and adjust to a six-man rotation, and you lose five starts and about 30 innings for your top pitcher(s). Most teams do not have a strong five-man rotation, so who picks up the extra 30 innings?
Now you are talking about diluting the starters and finding someone strong enough not to be an albatross in the rotation, causing your bullpen to be affected by any lapses or poor starts.
PRO:
Another fairly obvious benefit to a six-man rotation is the reduction in injury risk. Assuming your starting pitcher averages six innings per start, that comes out to 192 IP over a full season in a five-man rotation, and that number shrinks to 162 when a sixth starter is thrown into the mix, as stated above.
Padres starter Yu Darvish has even spoken out about this, highlighting the fact that six-man rotations are very common in Japan and their rates of Tommy John surgeries are much lower. Once again, there are stats to back up Darvish’s claims in an article published by FiveThirtyEight’s Rob Arhur.
He found that 1.7% of pitchers reported an injury within two weeks of making a start on three days rest. On four days rest, this number dropped to 1%, and, again, on five days rest, it decreased to just 0.8%.
To make it a little bit easier to understand, a pitcher who makes 25 starts on four days rest has a 5% greater chance of an injury that season as opposed to a pitcher getting five days rest.
CON:
Though it appears that pitching on extra days rest would be a benefit, there is not enough statistical data to really portray that into a benefit or not.
Over the course of the season, you are saving about 6.5 runs and a 0.3 percentage point increase in strikeouts, but also a 0.15 increase in walks, according to FanGraphs. Based on the Orioles’ projections by FanGraphs, there is a difference of a 0.21 increase for a sixth starter, with an increase of 3.5 runs also projected.
The ability to limit the innings means less pitches that the pitcher is throwing. Of course, the thought process is that this means less high velocity pitches. With pitchers throwing harder in today’s game, the extra rest may have starting pitchers throwing harder more, now that they are essentially pitching less.
So losing the innings could still apply the stress on the arm as pitchers will be more inclined to throw harder still applying the same stress, pitch limits or not.
PRO:
While it’s expected for a six-man rotation to place a much larger tax on a team’s bullpen, it’s almost had the opposite effect for the Orioles. Although it’s hard to pinpoint an exact date, the Orioles moved to six starters, for the sake of this article, August 12th, the day Cole Irvin got the start in Seattle.
In that time frame, the Orioles have pitched to a 3.10 ERA, a 1.16 WHIP and a 7.65 H/9, making it arguably their best statistical month on the pitching side thus far. Their starters have gone five or more innings in 14 out of 16 games in the month of August, and if you take out Kyle Gibson and Jack Flaherty’s recent blunders, Oriole starters are pitching to a 3.11 ERA for the month.
The length they have been able to get out of the starters has actually made life easier on the bullpen, getting Canó and Bautista some very important rest as the team gears up for the final stretch of a neck-and-neck AL East race.
CON:
If you take the taxing that the bullpen will face going with a sixth starter, the O’s bullpen has actually suffered since the sixth starter has been implemented.
Take components of the bullpen, based on the start of August for this argument.
- Félix Bautista: 5 G, 1-1, 3-of-4 in saves, 5.2 IP, 7.94 ERA, 2.12 WHIP, .318 AVG
- Mike Baumann: 8 G, 1-0, 8.2 IP, 4.15 ERA, 1.50 WHIP, .258 AVG
- Shintaro Fujinami: 7 G, 0-0, 1-of-1 in saves, 5.2 IP, 7.94 ERA, 1.41 WHIP, .150 AVG
- Nick Vespi: 3 G, 1-0, 3.2 IP, 7.36 ERA, 1.91 WHIP, .375 AVG
For the month of August, the Oriole bullpen has combined for 51 innings and has gone 4-1 with four saves in five chances across 16 games. They have accumulated a 3.00 ERA, allowing 27.8% of runners to score, walking 3.00 batters and allowing a .279 BABIP.
The extra starter takes an arm out of the bullpen, applying more stress on pitchers and, as seen above, causing skewed stats over a 16-game stretch that has seen a sixth starter used twice.
While history has shown that teams have utilized a six-man rotation, it should be noted that not one team has ever gone a full season with an extra starter.
There are two sides to the argument, but ultimately, there is limited data to prove the effectiveness. With pitchers being monitored for pitch counts, total innings and workload management, a new era is underway in the form of pitching.
Whether or not it transpires into six-man rotations is still something to watch. What do you think? Let us know in the comments below! Make sure to follow The Baltimore Battery on Facebook, Twitter and TikTok, and use the hashtag #baltimorebattery when sharing our content!
Like Stephen’s content? Follow him on Twitter – @SRJHeckman and listen to his O’s podcast, The Final Strike, anywhere you get your podcasts!
Like RJ’s content? Follow him on Twitter – @blaw690
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