MLB Teams Adapt Pitcher Usage Patterns To Era Of Max Velocity
Image credit: Tom Glavine (Photo by George Gojkovich/Getty Images)
Major League Baseball is always evolving.
New data streams and on-field conditions spur changes in just about every facet of the game, seemingly more rapidly than ever before.
I took a look at a series of global MLB trends that are changing before our eyes, many slowly enough to avoid detection. In this installment, the focus is pitcher usage patterns over the past quarter century or so. I chose 1998 as an endpoint because it is the beginning of the 30-team era. Only 162-game seasons were factored.
Baseball-Reference Stathead and FanGraphs Major League Leaders were invaluable to this exercise.
Starters receive more rest between starts
Major league starters toe the rubber with a full five days of rest in record numbers today.
According to a Baseball-Reference Stathead query, a total of 1,987 starts were made with five days of rest in 2023.
That corresponding number in 1998 was 1,319.
Source: Baseball-Reference Stathead
This means that major league teams stay on-rotation to a much higher degree today than they did 25 years ago. They tend not to skip turns in the rotation when the schedule allows, instead giving a more or less equal share of starts to each rotation spot rather than skipping back-end arms to funnel more turns to No. 1, 2 or 3 starters.
This is apparent by looking at the data in another way.
Five times as many pitchers made 33 or more starts in 1998 (45) as compared with 2023 (nine). This is notable because pitchers on a strict five-man rotation make 32 or 33 starts over 162 games.
So it’s clear that teams value the routine of a strict five-man rotation more than ever. It allows for maximum rest between starts, perhaps as a concession to the max-effort, max-velocity pitching approach.
This is in contrast to the more flexible rotation model of the past.
For example, the 1996 Braves skipped starts when possible in order to get Tom Glavine on the hill 36 times and to start Greg Maddux and John Smoltz 35 times each.
The 2001 Athletics followed suit. Tim Hudson and Barry Zito took 35 turns. Mark Mulder took 34.
The last team to have two pitchers make at least 35 starts was the 2006 Braves, with—who else?—Hudson and Smoltz.
Relievers are pitching less often on back-to-back days
Just as starting pitchers are working with more rest days between turns, relievers too are being deployed in a way that emphasizes rest between appearances.
In particular, relief appearances on back-to-back days are on a sharp decline.
In each season since 2018, the number of relief appearances made with zero days of rest has decreased. This means that teams are more sparingly working relievers in consecutive games—and also negating that possibility in some cases by more liberally optioning the last man in the bullpen to Triple-A and recalling a fresh arm.
Other factors are contributing to this trend, including the emergence of bulk relievers and multi-inning middle relievers who require rest in between appearances. The extinction of the one-out lefthanded matchup reliever also removes an entire subset of frequently-used pitchers.
No matter the reason, the number of relief appearances made with zero days of rest accounted for just 15.9% of all relief appearances in 2023. That is handily the lowest rate of the 30-team era.
Source: Baseball-Reference Stathead
While the number of total relief appearances has declined year-over-year in both 2022 and 2023, there are still many more relief appearances today than there were 25 years ago. In fact, there were 3,809 more of them in 2023 compared with 1998.
The rate of back-to-back relief appearances peaked in 2007, when 23% of relief appearances were made with zero rest days in between. In that season, 11 different pitchers made at least 80 relief appearances. Not a single pitcher reached that threshold in 2023.
Since 2007, the rate of relief appearances on zero days of rest has steadily tapered down, to 20.8% in 2013, to 18.6% in 2018, to 15.9% last year.
As is the case with starting pitcher workloads, teams appear to be prioritizing rest periods as a concession to a max-effort, max-velocity pitching style.
Pitchers throw harder than ever
If a picture is worth a thousand words, then this one helps explain why teams are building in more pitcher rest.
Source: FanGraphs Major League Leaders
In addition to pitchers throwing harder each season, they also throw their hardest more often. As The Athletic’s Eno Sarris has noted, pitchers’ velocity today sits closer to their max velocity than ever before.
In plain language, pitchers today are exerting maximum effort and maximum velocity far more often than they once did.
All that extra stress on pitchers’ arms has influenced usage patterns. Teams have determined that more rest between appearances is a concession they are willing to make in the name of greater velocity.
