Mid Season Pitcher Workloads

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.

2016 All Star Break Workloads
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
SOURCE: PITCHf/x

And, here’s what they looked like at the end of the season.

2016 End of Season Workloads
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 Chris Sale 21.51 5.84 1.21 32 232 32 0 0 3417
2 Nate Jones 20.27 2.56 1.98 71 90 12 32 27 998
3 Max Scherzer 20.16 5.48 0.76 34 231 34 0 0 3555
4 Dellin Betances 20.15 2.52 1.64 72 85 12 36 24 1224
5 Travis Wood 20.13 2.38 1.44 77 93 7 45 25 1015
6 Zach Duke 19.84 2.23 1.21 81 95 6 49 26 1014
7 Andrew Miller 19.44 2.62 1.57 69 83 9 41 19 1105
8 Seung Hwan Oh 19.26 2.45 1.42 75 86 9 45 21 1305
9 Chris Archer 18.93 5.59 0.67 33 209 33 0 0 3405
10 Juan Nicasio 18.84 3.36 2.27 52 126 16 27 9 2168
11 Randall Delgado 18.71 2.32 1.16 79 100 4 53 22 1351
12 JC Ramirez 18.52 2.36 1.34 70 89 7 45 18 1237
13 Madison Bumgarner 18.03 5.42 0.56 34 232 34 0 0 3547
14 Johnny Cueto 17.92 5.53 1.30 32 225 32 0 0 3290
15 David Hernandez 17.88 2.61 1.33 70 84 7 47 16 1274
SOURCE: PITCHf/x

So halfway point doesn’t necessarily indicate that you can linearly extrapolate the workload for the rest of the season, but you do see that 9 of the 15 all start break workload leaders ended up being in the top 15 at the end of the season.

So, how are things looking in 2017?

2017 All Star Break Workloads
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 Enny Romero 14.18 2.71 1.93 36 49 6 19 11 713
2 Felipe Rivero 14.17 2.23 1.09 44 55 1 28 15 696
3 Chris Sale 12.60 5.41 0.62 18 129 18 0 0 1953
4 Shane Greene 12.33 2.29 1.25 43 56 3 28 12 661
5 Chris Devenski 12.28 2.76 1.30 35 59 4 24 7 802
6 Brian Duensing 12.26 2.50 1.58 35 51 6 18 11 647
7 Corey Knebel 12.24 2.31 1.47 43 48 5 24 14 782
8 Andrew Miller 12.16 2.67 1.57 37 51 7 19 11 671
9 Mychal Givens 11.83 2.67 1.31 37 57 4 27 6 728
10 Bryan Shaw 11.81 2.34 1.15 42 54 3 27 12 645
11 Jim Johnson 11.67 2.51 1.46 38 40 6 18 14 626
12 Anthony Swarzak 11.65 2.56 1.50 35 57 4 22 9 642
13 Dan Jennings 11.61 2.30 1.14 41 62 3 28 10 637
14 Carlos Martinez 11.54 5.65 0.79 18 119 18 0 0 1738
15 Edwin Diaz 11.45 2.79 1.70 35 41 8 15 12 626
SOURCE: PITCHf/x
Felipe Rivero has and Enny Romero have factored into their respective teams as stabilizing forces on teams without a lot of bullpen depth. Rivero has appeared in more innings than anyone else on this list, but manages to have thrown the 7th most pitches. He does this by throwing only 12.7 pitches per inning appearance – a great way to reduce fatigue effects. The biggest demand he’s facing is the shortest average time between appearances on this list – only 2.23 days between games, and 15 back to back appearances on the season. This high workload doesn’t appear to have any effect on Rivero – he is still throwing absolute gas, and looks to be getting stronger (Figure 1).

Figure 1. Felipe Rivero – Velocity by Month

If you’d like to take a look at the rest of the workload numbers, you can find them here.
Fatigue Units can also be used to look at how hard starting pitchers are working, and how efficiently bullpens are being used.
2017 Starter Workloads by Team
Team Fatigue Units Pitches
1 Rockies 50.45 8432
2 Diamondbacks 49.82 8546
3 Nationals 49.02 8850
4 Giants 47.94 8664
5 Red Sox 47.68 8758
6 Cardinals 46.94 8145
7 Angels 46.67 8261
8 Astros 46.16 8108
9 Indians 45.72 8040
10 Mets 45.50 8072
11 Rangers 45.44 8218
12 Dodgers 44.89 7972
13 Pirates 44.55 7786
14 Mariners 44.36 7869
15 Twins 44.09 7943
16 Yankees 43.81 7797
17 Orioles 43.50 8442
18 Rays 43.45 8582
19 Padres 43.35 7641
20 Cubs 43.34 8051
21 Tigers 43.22 8373
22 Brewers 43.16 8237
23 Athletics 42.95 8114
24 Royals 42.24 7850
25 White Sox 42.15 8137
26 Braves 41.95 7919
27 Blue Jays 41.58 7994
28 Marlins 40.81 7441
29 Phillies 40.19 7954
30 Reds 38.47 7600
SOURCE: PITCHf/x

This table indicates a few things; the first being – The Rockies starters are doing incredible work this year. They are absolutely crushing it, in an environment that has been so traditionally hard on pitchers. It may be that the offence has been so good, the pitchers are being given a bit more leash. Any way you slice it, they’re sparing their bullpen, which will likely be called upon frequently in the second half, as the young Rockies starters get a break from time to time. On the other end of this – you can see that the terrible Blue Jays, Phillies, and Reds rotations aren’t getting overworked, because most of the time – their starters are getting shelled, and are out of the game early.

Now with the Bullpens, you can see some interesting trends;

2017 Reliever Workloads by Team
Rank Team Fatigue Units Back to Back Appearances Pitches
1 Mets 79.12 81 5259
2 Pirates 76.35 63 5092
3 Marlins 76.21 65 5606
4 Brewers 74.70 71 5651
5 White Sox 73.12 55 5099
6 Blue Jays 72.65 58 5108
7 Padres 71.56 52 5044
8 Braves 70.91 60 4559
9 Orioles 70.13 51 5455
10 Indians 70.02 64 4412
11 Astros 69.73 49 5124
12 Cubs 68.54 47 5173
13 Cardinals 68.47 54 4874
14 Reds 68.16 36 5460
15 Athletics 67.41 50 5120
16 Phillies 67.01 56 4819
17 Royals 66.52 51 4838
18 Mariners 66.34 53 4885
19 Dodgers 66.10 57 4901
20 Angels 65.99 49 4916
21 Rockies 65.62 49 4817
22 Diamondbacks 65.44 58 4497
23 Yankees 64.45 40 4802
24 Twins 64.33 53 5043
25 Nationals 62.27 51 4151
26 Red Sox 62.21 42 4699
27 Rays 61.42 41 4778
28 Tigers 61.07 46 4711
29 Rangers 60.85 44 4679
30 Giants 60.02 47 4456
SOURCE: PITCHf/x

First and foremost – the Mets are running their bullpen into the ground. They have a signficant lead in fatigue units over the second place team, and a massive lead in back to back appearances from their bullpen pitchers (81 times this year, a pitcher has come into a Mets game having pitched the day before). That seems… drastic. The Brewers are next, with 71 back to back appearances, and then the values seem to level off.

Once again – this is hardly a kiss of death for pitchers. This was an attempt to present a more physiologically representative method of workload demands on pitchers. You don’t need to go add and drop anyone any time soon because of this list – but if it comes down to one hot hand vs. another in your playoff matchups, you might want to go with the reliever with more gas left in the tank.





Ergonomist (CCPE) and Injury Prevention researcher. I like science and baseball - the order depends on the day. Twitter: @DrMikeSonne

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EonADS

The use of that meme is ruthless. I approve.