Fatigue units attempt to physiologically represent the workloads pitchers face. This includes velocity, days of rest, pitches per inning, and even the pace they pitch. Pitchers with extreme workloads were 2.7x more likely to have Tommy John surgery when compared to pitchers with moderate workloads. Who has worked the hardest in 2017?
At the midway point of the season, it’s always interesting to see how teams are utilizing their pitching staffs. I’ve been examining workloads through the metric I created, called Fatigue Units. This metric accounts for days between appearances, stress during pitching, and time between pitches – you can read more about it here. TLDR; Fatigue Units appear to be a more accurate indicator of “overworked” pitchers than pitches, or innings pitched.
To start off – what does the midway point indicate about a pitcher’s workload? It doesn’t necessarily indicate what the workload will be by season’s end, but it does say that the pitcher has worked hard in the first half. It definitely says that the team has trusted that pitcher, and, that pitcher is very good. Here’s what the halfway point workloads looked like in 2016.
| Rank | Name | Fatigue Units | Average Days Between Games | SD of Days Between | Games Appearances | Inning Appearances | 5 or More Days Rest | 2 – 4 Days Rest | 1 Day Rest | Pitch Count |
|---|---|---|---|---|---|---|---|---|---|---|
| 1 | Nate Jones | 14.46 | 2.42 | 1.93 | 49 | 63 | 8 | 21 | 20 | 685 |
| 2 | Travis Wood | 14.15 | 2.34 | 1.48 | 51 | 64 | 6 | 27 | 18 | 693 |
| 3 | Chris Sale | 13.85 | 6.05 | 1.47 | 20 | 144 | 20 | 0 | 0 | 2117 |
| 4 | David Phelps | 13.48 | 2.37 | 1.32 | 50 | 61 | 6 | 29 | 15 | 923 |
| 5 | Max Scherzer | 13.44 | 5.52 | 0.87 | 22 | 150 | 22 | 0 | 0 | 2327 |
| 6 | Seung Hwan Oh | 13.36 | 2.27 | 1.13 | 52 | 57 | 4 | 33 | 15 | 895 |
| 7 | Zach Duke | 13.14 | 2.23 | 1.26 | 53 | 62 | 5 | 31 | 17 | 615 |
| 8 | Dellin Betances | 12.94 | 2.33 | 1.48 | 49 | 56 | 5 | 30 | 14 | 817 |
| 9 | Ryan Pressly | 12.68 | 2.35 | 1.32 | 50 | 63 | 3 | 33 | 14 | 843 |
| 10 | John Lackey | 12.39 | 5.60 | 0.88 | 21 | 141 | 21 | 0 | 0 | 2099 |
| 11 | Chris Archer | 12.22 | 5.43 | 0.60 | 22 | 135 | 22 | 0 | 0 | 2254 |
| 12 | David Hernandez | 12.04 | 2.50 | 1.28 | 47 | 55 | 5 | 30 | 12 | 832 |
| 13 | Johnny Cueto | 12.04 | 5.42 | 1.38 | 21 | 151 | 21 | 0 | 0 | 2226 |
| 14 | Madison Bumgarner | 12.03 | 5.43 | 0.60 | 22 | 154 | 22 | 0 | 0 | 2331 |
| 15 | Bud Norris | 12.02 | 4.11 | 1.76 | 28 | 109 | 15 | 12 | 1 | 1693 |
On the last MASH report, I discussed Alex Wood’s S/C joint sprain, and many of the commenters claimed it was #FAKENEWS.
Traditional pitching metrics, such as innings pitched, and pitch counts, have often missed the mark when it comes to preventing pitcher injuries. As a result, I developed the Fatigue Units metric – which shows promise in illustrating how extreme workloads can influence pitchers in the subsequent seasons.
As a quick refresher – Fatigue Units are calculated by looking at an interaction between the number of pitches thrown, the velocity they are thrown at, the time taken between pitches, and the number of days between appearances. In the 2015 and 2016 season – these were your FU leaders.
| Rank | Name | 2015 | 2016 | Total |
|---|---|---|---|---|
| 1 | Travis Wood | 24.48 | 20.13 | 44.61 |
| 2 | Dellin Betances | 24.13 | 20.15 | 44.28 |
| 3 | Chris Sale | 21.92 | 21.51 | 43.43 |
| 4 | Max Scherzer | 20.38 | 20.16 | 40.54 |
| 5 | Chris Archer | 21.18 | 18.93 | 40.11 |
| 6 | Johnny Cueto | 21.85 | 17.92 | 39.77 |
| 7 | Jeurys Familia | 21.04 | 17.97 | 39.02 |
| 8 | Yordano Ventura | 19.49 | 19.24 | 38.73 |
| 9 | Jake Arrieta | 21.70 | 16.55 | 38.25 |
| 10 | Randall Delgado | 19.26 | 18.71 | 37.98 |
| 11 | Roberto Osuna | 18.00 | 19.82 | 37.82 |
| 12 | Cole Hamels | 19.93 | 17.57 | 37.50 |
| 13 | Brad Brach | 18.14 | 19.15 | 37.29 |
| 14 | Zach Duke | 17.12 | 19.84 | 36.97 |
| 15 | Addison Reed | 15.54 | 21.17 | 36.72 |
| 16 | David Price | 19.45 | 17.22 | 36.67 |
| 17 | Erasmo Ramirez | 17.74 | 18.83 | 36.57 |
| 18 | Hector Santiago | 19.95 | 16.60 | 36.55 |
| 19 | Kyle Barraclough | 15.99 | 20.50 | 36.48 |
| 20 | Madison Bumgarner | 18.35 | 18.03 | 36.38 |
Per Baltimore Orioles: Zach Britton on 10-day DL w left forearm strain. RHP Stefan Crichton recalled from Triple-A Norfolk. (cc: #BlueJays)
— Laura Armstrong (@lauraarmy) April 16, 2017
Hot off the press, the world’s best relief pitcher has been sent to the Disabled List with a dreaded forearm strain. A strain, for those of you not familiar, is the tearing of a muscle or a tendon. This is a big deal in the forearm, particularly for a pitcher, because these muscles are the ones that protect the UCL during the pitching motion.
We are all familiar with the performance Zach Britton put out in the 2016 season – arguably, one of the most dominant relief pitching performances of all time. What was happening under the hood to lead to this injury?
Tom Verducci once wrote about how a 30% increase in innings pitched could lead to injury in young pitchers. Since he wrote that, many people have objectively determined that this is not the case (Carleton, 2013). Not all innings are created equally, and not all pitches put the same amount of stress on the human body.
As we have learned in many different ways that are not a lot of fun , both relief pitchers and starting pitchers can succumb to the effects of pitching (also read as, getting injured). This makes the Pitcher Abuse Point scale not appropriate for relief pitchers (see this article on Baseball Prospectus – (Jazayerli, 1998)). Other research has pointed to measures like innings pitched as being a poor determinant of workload in pitchers (Karakolis et al., 2016). Pitching on consecutive days, high velocities, and total pitches have been identified as risk factors for injury (Whiteside et al., 2016). Read the rest of this entry »