Earlier in the year I observed that CC was getting significantly more groundballs than earlier in his career. At this time we can see that he has maintained this new approach throughout the year (via fangraphs):
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|2009||Yankees||1.15||19.8 %||42.9 %||37.3 %|
|2010||Yankees||1.47||14.8 %||50.7 %||34.5 %|
Now I would like to explore why he is getting more groundballs.
The most obvious explanation is that CC is simply leaning more heavily on his pitches that induce groundballs. Indeed, this appears to be the case, as he is throwing his sinker/two seamer more this year than last (via Trip Somers’ pitch f/x tool):
FF= four seam, CH=changeup, SI=sinker/two seam, SL=slider, CU=curveball
I elected to use this pitch f/x tool because I’m fairly sure this pitch f/x classification system has not changed from last year to this year, unlike the Gameday classifications (Gameday has changed it’s classifications of fastballs over the years, particularly altering fastball classifications into more specific categories like sinkers and cutters).
As you can see, he’s throwing basically the same amount of breaking balls and changeups, and has simply replaced some of his fourseamers with sinkers/two-seamers.
Yet this change in pitch selection does not completely explain his increase in GB% rate. The individual groundball rates of his pitches have changed:
*In case you’re wondering, the curveballs dissapeared because I just grouped them with the sliders.
It appears that the groundball rates of his changeup and sinker have not changed that much, while his FF and SL are both getting more groundballs this year.
Perhaps this year he is simply just pounding the bottom of the zone, resulting in more groundballs?
It doesn’t look like his pitch location is all that diferent. Perhaps in 2010 he’s throwing the ball to the outer third of the plate (from the perspective of a right handed batter) a little more, but that’s about it. And sure enough, when I look through the numbers I find that 37.3% of his pitches in 2009 were at the bottom third of the zone or lower, and in 2010 36.5% of his pitches were in the bottom third of the zone or lower.
It’s also possible that while his pitch location hasn’t changed that much, that batters are just swinging more at pitches that are low in the zone, leading to more groundballs.
Inside the black circle represents the area where batters swing at least 50% of the time. You can ignore the outer lines. the orange line is the bottom third of the zone.
These two swing charts look almost identical, leading me to believe that where the batters swung had no part in CC’s increase in groundballs.
The last factor I’m going to look into is the movement of the individual pitches.
There are two primary groups of pitches here. The first group is compromised of CC’s fastballs (red), sinkers (pink), and changeups (purple). The second cluster consists of CC’s breaking balls (red and green).
As you can see, in 2010 his curveballs and sliders appear to have lost some horizontal movement (the chart is from the perspective of the catcher and does not account for gravity), but have gained some vertical drop. This seems like a sufficient explanation for the increase in groundball rate of his slider/curve; the increased downward action of his breaking balls is causing batters to get on top of the ball more often.
His fastballs (FF and SI) seem to have a larger spread of horizontal movement. It is possible that this helps CC induce weak contact when he throws fastballs, explaining the higher GB%. Another explanation is that pitch f/x just has missclassified some of his sinkers as fourseamers, which would indicate that he’s actually throwing more sinkers than the pitch f/x classifications say he does.
CC seems to have gotten oppposing batters to chop the ball into the ground more often this year, primarily by throwing more sinkers and by modifying the movement of his breaking balls. In my opinion, these changes are a boon to CC and the Yankees, as the groundball centric approach should extend the longevity of his career as his stuff diminishes and he relies less on being a power pitcher.
This article was originally posted at pendingpinstripes.net