Pitch Counts, Innings Limits, and Jake Arrieta

Just a few weeks ago, the Cubs indicated that Jake Arrieta would have his first spring start delayed, in part out of a desire to place some limit on his workload this season. Arrieta has made it clear that he’s fine with this, and that he sees the value in some mindfulness about his workload in 2016. Now, there’s a few ways of looking at this. Recently, our own Ryan Davis detailed the strain that Arrieta’s use of the “slutter” might put on his elbow, and that’s certainly worth keeping an eye on. However, given that Arrieta also pitched nearly 100 more innings in 2015 than he did the previous year (which in itself was a 40-pitch increase) pitch choices aren’t the only things worth monitoring when it comes to Arrieta.

The idea behind limiting a pitcher’s total innings in a season has a bit of an unclear history. Not very long ago, pitchers did not have the restraints on them that are often in place today, and definitely didn’t have clear innings caps like what the Washington Nationals put in place for Stephen Strasburg just a few seasons ago. In fact, pitchers of lore often threw far, far beyond what modern hurlers do. For instance, a personal favorite of mine, Old Hoss Radbourn, threw nearly 700 innings in his 1884 campaign. It should be noted that he never came close to that total in his career afterward, and it probably helped to spell the downward trajectory of his career. Really, his best two years were 1883 and 1884, in which he threw about 1,300 innings combined. And, of course, the game was different then.

The development of specific pitch count limitations is a bit more clear, however, as a 1998 Baseball Prospectus article put forth the idea that the number of pitches might be having a negative impact on pitcher health when not carefully monitored. In 2010, Anna Floch illustrated the change in pitch count philosophy as it was increasingly impacting minor league pitchers. In her piece, she noted that the “magic number” for a start is somewhere around 100 pitches, which is a number we’ve come to expect and understand in the years since. Not everyone agrees fully with this idea, however, as Perry Arnold claimed in 2009 for Bleacher Report that pitchers were just simply being “babied” from the lower ranks of the minor league organization to the top, and simply were not learning to go deep into games. For Reuters in 2012, Ivan Oransky posited that pitch counts aren’t really the cause of injury in young pitchers, and Nolan Ryan chimed in a few years ago in agreement.

Ultimately, it’s difficult to find a consistent understanding of what works and what doesn’t in terms of monitoring pitch counts and innings thrown, but in terms of fatigue, the Cubs are clearly looking to try and avoid tiring out their star pitcher with too much work during the course of spring training and the regular season. They intend to play deep into October, after all. While the Cubs may not strictly limit Arrieta’s innings, a closer monitoring of his pitch counts and how deep into games he’ll go this year is probably going to happen. In an article on ESPN a few weeks ago, he acknowledged a personal desire to finish the games that he started in 2015: “Last year my mindset was I want the eighth or ninth inning every time out.” He went on to admit to feeling “a bit out of gas” in his last two starts of the postseason.

As I mentioned earlier, Arrieta spent a lot more time on the mound last season than he ever has before, and this creates a bit of uncertainty about how he will react going forward. To attempt to get an idea of how this has affected players in the past, I turned to the research team at Baseball Prospectus for some help with a bit of precedent in this regard. Here’s a list of pitchers who have seen 100+ innings spikes since 2000:

Pitcher Name Year 1 IP Year 2 IP
33 Roy Oswalt 2003 130.3 2004 237.0
217 Woody Williams 2002 108.3 2003 220.7
304 Randy Johnson 2003 128.0 2004 245.7
1619 David Wells 2001 100.7 2002 206.3
16660 Chris Capuano 2004 101.7 2005 219.0
31361 Adam Wainwright 2008 132.0 2009 233.0

For the sake of keeping these comparisons as similar as possible (though they can’t be exact, of course), let’s look at how the following year went in terms of each pitcher’s WARP and DRA:

Pitcher Year IP WARP DRA
Roy Oswalt 2005 241.7 3.5 (down from 5.5 in 2004) 4.16 (up from 3.64 in 2004)
Woody Williams 2004 189.7 1.4 (down from 4.5 in 2003) 5.11 (up from 3.87 in 2003)
Randy Johnson 2005 225.7 4.8 (down from 8.8 in 2004) 3.58 (up from 2.49 in 2004)
David Wells 2003 213 2.5 (down from 2.9 in 2002) 4.62 (up from 4.33 in 2002)
Chris Capuano 2006 221.3 3.1 (up from 1.1 in 2005) 4.50 (down from 5.04 in 2005)
Adam Wainwright 2010 230.3 5.4 (up from 3.5 in 2009) 3.23 (down from 4.16 in 2009)

That’s fairly inconclusive. For comparison’s sake, in 2015, Arrieta threw 229 innings and was a 7.4 WARP pitcher with a DRA of 2.31. This was up from 156.7 IP, 4.7 WARP, and 2.33 DRA the previous year.

The bottom line is that it’s not obvious just what will happen with Arrieta in 2016. PECOTA projects him to look at lot more like he did in 2014 than he did last year, which might disappoint some people, but it’s worth noting that he was a very good pitcher that year. And in looking at some of these prior examples of pitchers who have seen sudden jumps in their innings totals, some saw dips in performance the following year and some continued to improve. Which tell us … what? Not much, I think. The sample sizes are so small, and human beings so idiosyncratic, that a lot of this will come down to Arrieta himself, and how he approaches the season. That stuff matters. About five months ago, Sahadev Sharma wrote about the intangibles that go into these decisions sometimes, and those’ll be especially important for Arrieta, who’s honed the mental side of his game to a fine point. Which is why, in the end, the most important thing pointing in a positive direction for Arrieta might be that he has already bought into the idea that he needs to keep himself rested and ready. That could be enough.

Lead photo courtesy Mark J. Rebilas—USA Today Sports.

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3 comments on “Pitch Counts, Innings Limits, and Jake Arrieta”


It’s worth noting that pitches and innings are not all equal from a fatigue standpoint. One can easily argue that in addition to often working late into games last season Arietta was also often pitching in high leverage situations. The WC game in Pittsburgh is a good example. Those 113 pitches were a reasonable pitch count under most circumstances but there’s no surprise he was more exhausted at the end of that game versus a typical 113 pitch outing.

For Jake going forward, the difference between 2015 and 2016 is going to hinge on the Cubs place in the standings. Rather than fighting for the WC, presumably the Cubs will be winning the division so having games of high importance down the stretch in September will not be a concern (like, 123 pitches on Sept 22). The Cubs will be able to pitch him on regular rest and keep his pitch count down in games to keep him fresh for the playoffs.

Jared Wyllys

Very important, for sure. The emotional aspect of it is something that is interesting, but really hard to measure, if we can at all. But you’ve made a good point. 113 pitches on a Saturday in June, for a generic example, is not like 113 pitches in a wild card game in October.

It could be argued though that while the Cubs were not winning the division last year, their playoff spot was pretty safe for the last few weeks of the season, so the strain of some of those September games may not have been as severe as we think.


Jake HATED being taken outta games all last yr, and could sometimes be seen arguing w/ Joe on the point. It sounds like he will be more amenable to such things this yr, wisely so.

Our offense will be better this yr, our defense already is, and the same for our pen. All 3 factors spell fewer innings, less leverage, more rest, more health…and more dominance from all our starters come Oct.

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