Comparing Kuroda’s Pitch f/x Numbers from Start to Start
After his first start of the season, Yankee fans were already quite worried that Hiroki Kuroda would be unsuccessful in his transition from the NL West to the AL East. His command was all over the place and he was hit extremely hard by the Rays. He was immediately criticized as not being cut out to pitch in the heavy hitting AL East. However, Kuroda may just have silenced his critics with his terrific start yesterday. He looked very sharp and was able to keep the Angels’ hitters off balance in his 8 inning shutout. Now it doesn’t take a genius to know that one strong showing doesn’t foretell that a pitcher will pitch that way for the rest of the season. However, we can analyze his performance yesterday and determine what the key will be for maintaining a similar level of success.
Let’s make some observations, shall we?
— Average Speed - From start to start, Kuroda’s average speed on his pitches was pretty similar. If anything, his curveball against the Rays was a bit faster than versus the Angels, and his spliiter was a couple mph faster against the Angels.
— Max Speed - Like the average speed, the max speed was for the most similar from start to start, especially for his four-seam fastball and sinker. However against the Angels, Kuroda threw the slider with quite a bit more pop than in his first start. In addition, he juiced up the splitter a few mph against the Angels while throwing the curveball a bit slower.
— Average Horizontal Break - The general trend of the above statistics is that Kuroda’s four-seam fastball and variations (sinker and splitter) typically had a lot more horizontal movement in his start yesterday than in his start versus the Rays. This could be the reason why these pitches were quite a bit more effective yesterday. His faster pitches ran away from lefties and rammed in toward righties. On the other hand, Kuroda’s slider and curveball both moved much less in the horizontal direction in yesterday’s start.
— Average Vertical Break - What is somewhat surprising with these numbers is that Kuroda generated a ton more vertical movement in his terrible start against the Rays than in the effective one yesterday. It could be that the greater downward movement came at the cost of Kuroda’s command on April 7th. In that case, the sharper the movement we see from Kuroda’s pitches, the more success he will probably have across the board.
— Pitch Count - In his start yesterday, Kuroda relied greatly on the sinker/slider combination as evidenced by the above pitch totals. In general, he used his four-seam fastball much less and did a better job of mixing in his secondary pitches than he did against the Rays.
— Strikes % - It is fairly interesting that there is a correlation between the average horizontal break of Kuroda’s four-seamer, and sinker, and their percentage of strikes. In yesterday’s start, Kuroda threw those two pitches with better horizontal movement and command. Aside from that, he also threw the curveball and slider for a greater number of strikes against the Angels than versus the Rays which clearly was a help.
— Swinging Strikes % - The number of times Kuroda got swinging strikes with his pitches was fairly similar from start to start. However, this isn’t true in the case of his sinker. In the start against the Rays, the sinker got Kuroda 4 swinging strikes while that number was 0 in yesterday’s start. This is most likely a result of the sinker’s larger vertical break in the miserable April 7 start.
— Linear Weights - Linear Weights are pretty complicated but to put it simply, the lower the number, the better that pitch was. Therefore it is clear that all of Hiroki Kuroda’s pitches were more effective in the Angels start. The sinker specfically was a very nasty pitch yesterday for him with a linear weight of roughly -2.3.
Several conclusions can be drawn from these observations:
1) Less seems to be more in terms of vertical movement for Kuroda’s sinker. It was a much more effective pitch at a vertical break of 5.29 rather than 5.85.
2) When it comes to Kuroda’s four-seam fastball, sinker, and splitter, the more horizontal movement the better.
3) The less Kuroda uses the four-seamer and the more he mixes in his secondary pitches, the more effective he will be.
4) Kuroda doesn’t need to get swinging strikes with his sinker to have success. He seems to be at his best when he just throws the sinker low and generates ground-balls.
It is important to acknowledge that although these conclusions are well supported by the Pitch f/x data, this is still a pretty small sample size. The four above points won’t necessarily be true all the time, but the data does give us a good idea of what to look for in Kuroda’s future starts with the Yankees.