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.

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

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?

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).

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.