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The Day After

Publication Date: December 2, 2003

Why You Doing That?

One of the main questions we get here at Boyd's World World Headquarters of the World, after, "What the flibbertigiblets were you thinking when you wrote that?" and, "You going to finish that fried okra?", is, "Why would anybody do statistical analysis instead of just watching and enjoying the games?" The subtext, in our numeraphobic society, is wondering why anyone would voluntarily deal with a bunch of numbers when they didn't have to.

The meat in this week's column is a perfect example of why I do it -- there's truth buried in some of those numbers. I don't fiddle with the numbers just because I like numbers (although some days I do), I fiddle with them because properly arranged, they can teach us something about the game. What I'm always trying to do is figure out how to arrange them and then boil them down properly so that I come up with a useful result. Ideally, I'd like to get it down to a point where I could do a column consisting of one self-evident number with a short piece of explanatory text, but in the meantime you'll have to put up with me showing my work most of the time. This week, that means you get the following table:

ERA Before, During, and After Starts at Differing
Pitch Count Levels, 2003

Pitches  Games   Before   During   After   Increase

   50    10158    4.76     4.63     5.05     0.29
   60     9644    4.72     4.48     5.03     0.31
   70     8875    4.69     4.29     5.02     0.33
   80     7687    4.63     4.08     4.97     0.33
   90     6063    4.55     3.86     4.91     0.36
  100     4128    4.51     3.68     4.87     0.36
  110     2289    4.45     3.48     4.92     0.47
  120     1096    4.39     3.40     4.92     0.53
  130      416    4.48     3.63     4.93     0.45
  140      233    4.36     3.87     4.99     0.62
  150       71    4.10     4.34     5.40     1.30

There are two arguments against letting pitchers throw too many pitches in a game, however many may count as too many. The first is based on the increased potential for injury. We don't know enough to be definitive about the specifics of this, and, for the most part, it's an ethical question for college coaches since most of the risk comes after the player has departed. The second argument, though, is front and center for the coaches. It's that overuse makes pitchers less effective in following starts.

I thought it might be interesting to see what happens in the start after a high-pitch-count start. In the interests of getting a feel for that, I've produced the chart above. Each row includes all starts above a given number of pitches (within the usual constraints of missing data and so on), and the ERA's are cumulative across all those starts.

There are some interesting tangents in interpreting this. First of all, ERA essentially increased for the population of pitchers over the course of the season last year, more so than most years, so that has to be discounted in looking at the effects of high-pitch starts. On the other hand, the lower "during" numbers indicate that pitchers who go longer generally do so because they're pitching well (duh), so you might expect a followup performance boost the next week.

As it turns out, there is an effect that kicks in right around 110 pitches. It's not huge, although by the time you get to 140 pitches, you're looking at an ERA increase of about a third of a run. By the way, if you break it down to 5-pitch intervals instead (which I won't print to keep from throwing out too many numbers), the really big increase kicks in around 145 pitches. I'm not sure how useful that piece of information is, since I don't expect anyone to set a 145-pitch limit, but there it is.

So, how significant is, say, a .15 increase in ERA for the next start? Runs are discreet events, so you can't give up a sixth of a run. One good way of looking at it is that, if you do this half-a-dozen times over the course of the season, you're going to give up one extra run, which may or may not cost you an extra game. Balancing this against the good to be had from leaving your guy in when he's going well, which may well be worth more than one run, may well be a good bet.

I hate it when I don't get the answers I want. I'll probably do some further research when I get the chance -- I can look at 2002, for example, or see what the long-term effects past the next start are -- but for now there's no compelling argument here other than to keep your pitchers under 140 pitches.

An Addendum

In addition to last week's preview schedule, I had an interesting tournament pointed out to me. February 27-29, Coastal Carolina is hosting Baseball at the Beach, including CCU, Ohio State, Kent State, and Richmond. Although there are some RPI darlings in there, the odds are pretty good that at least two of those could be fairly good this year, and it should be worth a look.

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Boyd's World-> Breadcrumbs Back to Omaha-> The Day After About the author, Boyd Nation