F/X VisualizationsMay 13, 2009
Platoon Splits for Three Types of Fastballs
By Dave Allen

On Friday I looked at the run value of four-seam, two-seam and cutter fastballs based on pitch movement. In that post I noted, that it looked like two-seam fastballs had very extreme and cutters almost no platoon split. This comment was offhand, and I did not demonstrate that was the case. In this short post I will do that.

A month ago I looked at the platoon splits of fastballs, changeups, sliders and curves. My results reconfirmed what John Walsh showed in the 2008 Hardball Times Annual: fastballs have an intermediate platoon split, sliders a very extreme one, and changeups and curves none. In that post I grouped all fastballs together. Based on those results and the results of last week's post I was very curious to see the platoon splits for the different fastball types.


These results are consisitent with the remarks I made on Friday:

  • Two-seam fastballs have an extremely large platoon split, as big as the slider platoon split.
  • The platoon split for cutters is not statistically significant.
  • Four-seam fastballs have a small yet significant split.

Interestingly, there is no trend for pitchers to throw the pitches in different proportions to lefties and righties. Approximately 48% of all pitches are four-seam fastballs, 8% are two-seam fastballs and 4% are cutters with almost no difference in same- and opposite-handed at-bats for either RHPs or LHPs. This is very strange it would seem pitchers would do well to throw two-seams fastballs much more in same-handed at-bats, as they do with sliders, and cutters in opposite-handed at-bats, as they do with changeups.

One pitcher who does this, and I would guess this is a big reason for his success, is Jon Lester. Lester, a lefty, throws all three of these fastballs. Here are the proportion of pitches to RHBs and LHBs that are each of the three fastball types.

| Fastabll Type    |     RHB |     LHB | 
| Four-Seam        |   0.317 |   0.322 |
| Two-Seam         |   0.155 |   0.290 |
| Cutter           |   0.133 |   0.077 |

This is the type of breakdown I think pitchers should use, way more cutters to opposite-handed batters and more sinkers/two seamers to same-handed batters. I am surprised that is the not the case generally. It would be interesting to see if successful pitchers, like Lester, are more likely to show this breakdown than the average pitcher.


Great work Dave. You are the man. Boy, have you brought my interest in baseball back with a vengence. I lost almost all interest when the drug scandal hit, but then Dave's blog came along. Now for some business. I am interested in an analysis in the comparison of the movement and results of the spit ball when it was legal years ago with the earthball pitch now being used by a number of minor league pitchers. I think this would be of great interest to your audience. Keep up the good work.

Dave, this is great stuff. Is there a difference in the run values of fastballs thrown by guys who throw more sliders with big platoon splits versus guys who throw curveballs and changeups without big platoon splits? Perhaps preparing against the slider of a same-handed pitcher gives that pitcher an advantage in throwing the fastball even if it's movement is similar to the fastball/changeup pitcher?


Wow thanks for the kind words. I am glad that I could bring back your interest in baseball. Unfortunately the data I use to do this analysis only goes back to 2007. The retrosheet database that goes back much farther is only play-by-play and not pitch-by-pitch, so the analysis you suggest would be pretty tricky.


That is a really interesting question. I have not yet done any analysis like that. But I would really like to start looking into how pitcher's different pitch types interact.

The problem I have (as a former pitcher) is that these pitch-type statistics are simply NOT accurate. For example; "48% of all pitches are four-seam fastballs, 8% are two-seam fastballs". I promise you there is No Way in Hell that there are 6 four-seam fastballs thrown for every 1 two-seamer. It's about 50-50.


I think you are right that the pitch classification algorithms have a way to go. My pitch frequency breakdowns that you quote of the reclassified 07/08 fastballs are close to the frequency breakdowns for the 09 fastballs classified by the new pitchf/x classification algorithm. So at the very least my error is consistent with their error.

Some excellent analysis here, thanks. Most of the Red Sox pitchers have a marked tendency to use the 2-seamer primarily to same-handed batters: not just Lester, but also Beckett, Masterson and Matsuzaka. These are observations on a game-by-game basis over the last two years, not aggregated data. Word of mouth suggests that Buchholz is adopting the same approach in the minors. That seems to be part of the team's approach to developing pitchers' repertoires, and I credit a lot of that to pitching coach John Farrell.

The 2-seamer to opposite-handed hitters is used mostly in special situations: as a brushback sinker that tails back over the inside corner for a strike (also a Derek Lowe specialty), or where a double play is needed.


That is a really interesting observation. I am going to go back and check out if there is a trend for players on specific teams to use the two-seamers primarily to same-handed batters more than other teams. I wonder if certain teams, like the Red Sox, are more aware of the platoon split than others.

Thanks for pointing this out.