Did Bumgarner and Shields Throw Too Many Pitches?

Madison Bumgarner pitched quite a bit this past season. Including the regular and post season, he threw a total of 4,074 pitches, which wasn’t even the season’s top total; James Shields bested him by throwing six more, for a total of 4,080 pitches in 2014, not including spring training. So with all of the pitches thrown this season (and one month less of rest), how should we expect these two to produce next season? Let’s look at some comparable pitchers.

To get the information, I looked at all pitchers from 1995 to 2013 who threw at least 4,000 pitches. I found thirty of them. Randy Johnson showed up on the list five times, and Justin Verlander was second with four appearances. In all, 21 different pitchers made the list which ranged from Justin Verlander throwing 4,004 in 2009 to Randy Johnson using over 4,700 (!) in 2001. Livan Hernandez in 2005 was the only pitcher to top 4,000 pitches in just the regular season. Finally, these pitchers were on the older side, with their average age being over 31-years-old.

So here are the pitchers and the seasons I will be comparing

A.J. Burnett (2009), Adam Wainwright (2013), Al Leiter (2000), Barry Zito (2003), C.J. Wilson (2011), CC Sabathia (2009), Chris Carpenter (2011), Cliff Lee (2009), Curt Schilling (1998,2001), John Smoltz (1996), Jon Lester (2013), Justin Verlander (2009,2011,2012,2013), Kerry Wood (2003), Kevin Brown (1998), Livan Hernandez (2005), Pedro Martinez (2004), Randy Johnson (1995,1999,2000,2001,2002), Roger Clemens (1996,2001), Roy Oswalt (2005), Russ Ortiz (2002), Tim Lincecum (2010)

For each of these pitchers, here is their combined 4,000-pitch regular season numbers (no post season values) and how they performed the next regular season. Additionally, I have included Marcel projection for the high pitch count season and the one after it.

Note: For pitchers, I like using the median values because one high ERA can skew the value up. With these pitchers, the average and median values are too far off, but I will use median values from now on.

		4,000 pitch season		Next Season
		Marcel Projection	Regular Season	Marcel Projection	Regular Season
Median	ERA	3.58	3.21	3.36	3.27
	IP	190	238	200	217
	Age	31.5	31.5	32.5	32.5
Average	ERA	3.48	3.15	3.39	3.38
	IP	189	235	199	204
	Age	31.6	31.6	32.6	32.6

Going into the 4,000-pitch season, the group of pitchers were supposed to have an ERA just under 3.50 and throw about 190 innings. For these 30 pitchers, they hit the trifecta.

1. They out performed their ERA by 33 points. Every season some pitchers will do better than projected, others worse. These were the ones who did better, which is why they were allowed to throw so many pitches to begin with.
2. They were healthy. A pitcher doesn’t reach 4,000 pitches by taking a month off with a dead arm.
3. The combination of the #1 and #2 probably boosted the pitcher’s production enough to help their team reach the postseason, where their workloads were extended even further.

So now we look at how they performed the next season. As expected, they performed worse. Comparing season one to season two stats, their ERA jumped by 23 points and they threw 23 less innings. Then look at the projections, the ERA value is off by 1 point and the innings projection missed by 5. The projections where about dead on as a group. Via regression and aging, the pitchers performed worse, but their production didn’t fall off a cliff. Justin Verlander’s ERA underperformed his projections the most (projected 3.12 compared to 4.54 actual) while Roger Clemens was projected at 3.92 in 1997, but it ended up at 2.05. Only twice did a pitcher see his innings drop by more then 100 and each time it was Randy Johnson (1995 to 1996 and 2002 to 2003).

If a person wants a good idea of how James Shields and Madison Bumgarner will perform in 2015, after throwing 4,000 pitches in 2014, just look at their projections. They could under or over perform, but if history tells us anything, it’s that we should trust the projections.