Jeff Zimmerman of Fangraphs recently wrote an article examining how the accumulation of injuries in a career prematurely ages pitchers versus those pitchers that are better able to avoid injury. In conducting his research, Zimmerman only looked at starting pitchers, and he looked at injury accumulation from 2010-2018. He divided those pitchers that qualified under these criteria by steep production decline starting at age 29.
The steep production decline starting at age 29 for starting pitchers (and hitters for that matter) as a group has been born out by Zimmerman’s work in the Hardball Times. Zimmerman found that around age 29, starting pitchers begin to pitch much less effectively in a number of key outcomes including ERA-, BB%, HR/9, K%, and average fastball velocity. The effect was most pronounced in BB% and HR/9 as you can see below.
Digging deeper Zimmerman found that there is an injury threshold that seems to actually matter more than age in areas like ERA-, median IP difference, average IL days, and IL chance. The data he found suggested that starting pitchers that accumulated over 120 days on the IL declined faster than those starting pitchers that had not reached that threshold. His overall results showed the following:
So it seems, according to Zimmerman’s work, that an aging pitcher (decreasing ability in BB% and HR/9) coupled with 120 or more days of IL accumulation (increased ERA- and increased chance of further injury and time on IL) are indicative of a starting pitcher that teams should be concerned about. This concern should become even more pronounced if a starting pitcher has had his injuries primarily to the arm, elbow, or shoulder. He found more than two IL stints with arm, elbow, or shoulder injuries indicated even more dire results.
As Zimmerman said of these findings:
Even pitchers who had two or few IL stints weren’t in great shape with them averaging over 200 days on the IL. That third arm related IL trip can be a deal-breaker because the pitcher will, on average, will see their skill degrade about twice as fast as those with two or fewer trips.
There were 34 pitchers that fell into this category. Of those 34 pitchers, the Milwaukee Brewers’ free agent acquisition, Brett Anderson tops this dubious list of starting pitchers who should age faster than expected.
Brett Anderson has had six arm related IL stints in his career. He has missed a whopping 918 days due to injury. There really is no one close to Anderson on this list. There is no doubt David Stearns was gambling on what Anderson could bring to the table when he signed him to a 1-year, $5 million contract for 2020.
Anderson’s 2019 performance does offer hope for what how he could perform in 2020. For the Oakland Athletics, Anderson logged 176 innings with no injuries and pitched to a 3.89 ERA and a 4.57 FIP. Anderson fills a criteria that Stearns likes - he induces ground balls at a high rate, like his 54.5% GB rate last year. Anderson will have to keep the ball on the ground, because Miller Park does not play as big as the Oakland Coliseum.
What is unknown is how a 60-game season will impact starting pitchers, especially pitchers like Anderson. Will the shortened season help or hurt the pitchers that fall into the category of which Anderson tops the list? On the surface, one would think that it should help.
Anderson made 31 starts in 2019 in a 162 game season. Anderson is likely to only get 10-12 starts for Milwaukee in 2020, and that is if the Brewers’ use him every fifth day as a starter and he remains off the IL. With less use should come less risk for injury, right?
There is research out there that suggests that pitchers are more prone to injury early in a season. According to this research, there are two areas of concern for all pitchers. First, pitchers lose range of motion after not pitching over the offseason. This is theorized to play a potential role in increased pitcher injury. Until pitchers access their optimal range of motion, there is greater risk. Obviously ramping up becomes really important in these situations, and the Brewers have indicated they are on top of this.
Another theorized component that plays a role in increased pitcher injury concerns building the arm up to pitching every fifth day. Pitchers have to ramp up their throwing as the prospect of real competition comes closer. During that period as well as early in the season, pitchers are not at what is referred to as a chronic workload capacity. This is just a reference to how much a pitcher pitches over a 28 day span. The chronic workload increases as the season progresses, obviously. In theory the pitcher is less likely to have an injury as the chronic workload increases unless that workload becomes too much. It is suggested that there is an optimal level for every pitcher.
It is just going to be really uncertain across the board of how the shortened season will impact pitching. Pitchers essentially have to ramp up quicker so as to increase range of motion and achieve optimal workload. That in and of itself is apt to increase risk of injury.
Brett Anderson only needs to make a third of the starts he made in 2019 while pitching similarly to his 2019 numbers to be a viable member of the starting rotation. Unfortunately, the veteran lefty has spent more time on the IL than any other starting pitcher in MLB due to arm related issues. He is 32 years old. Like every other pitcher, he has to increase range of motion and workload safely to decrease injury risk, but he is just more vulnerable than most of the other pitchers in baseball due to his history.
What we can hope for is that he has a veteran’s ability to understand his body and his mechanics. It is possible that going through so much rehabilitation has increased his acumen beyond that of the normal pitcher. Let’s hope.
The gamble on Anderson is not that big a one. It is only one year. But what the Brewers get out of him is a major question mark.
Statistics courtesy of Fangraphs