From Mitchel Lichtman at Baseball Prospectus on November 15, 2013:
Last week, in this article, I discussed a starting pitcher’s “times through the order penalty” (TTOP)—the tendency for the pitcher’s performance to suffer with each trip through the lineup. In the comments section, several readers wondered whether pitchers who throw primarily one type of pitch might have a particularly large penalty as opposed to pitchers who throw a greater variety of pitches. The speculation was that it would be harder or take longer for a batter to acclimate himself to a pitcher who has a lot of different pitches in his arsenal. In addition, since most starters tend to throw more fastballs the first time through the order, pitchers who follow that up with a higher frequency of off-speed pitches might have an advantage over those who continue to throw mostly fastballs, in terms of the TTOP. Let’s see if that is true.
First I split all the starters into three groups: one, over 75 percent fastballs, two, under 50 percent fastballs, and three, all the rest. The data is from 2002-2012, and includes Baseball Info Solutions’ pitch-type information from FanGraphs. The results are illuminating.
Pitchers who throw mostly fastballs lose 47 points in wOBA against (columns eight plus nine) by the third time through the order. (For those who are just joining us, wOBA is an all-in-one offensive rate statistic in the same vein as TAv, but on the OBP scale instead of the BA scale.) Those with a much lower fastball frequency lose only 18 points. Interestingly, the “fastball” group reverts back to better-than-normal levels the fourth time (I don’t know why that is, but I’ll return to that issue later), but the latter group continues to suffer a penalty as do all the others. Keep in mind that the fourth time numbers represent very small samples for the first two groups, since starters don’t often make it past the third time through the order.
The takeaway here is that a starter’s pitch repertoire is extremely important in terms of how long he should be left in the game and whether he should start or relieve (we already knew the latter, right?).
Read the full article here: http://www.baseballprospectus.com/article.php?articleid=22235
Originally published: November 15, 2013. Last Updated: November 15, 2013.