In the previous post on Ubaldo Jimenez, we noted that his slider was getting hit harder by RHB in the second half of the season. Not unrelated, he was striking out fewer RHB on the pitch as well.
Before we focus on just his slider versus RHB, let's compare his expected numbers on the pitch for all batters, which factor in all sliders thrown:
We don't see much difference between his expected numbers from the two halves of the season. His actual line on the pitch went from .130/.259/.174 to .262/.340/.333. The fact that his expected line remained stable while his actual line jumped a bit tells us that he was having trouble using his slider as an out pitch. When we isolate RHB, we see where he had the most trouble.
Again, we see that his slider was fairly effective throughout the season in setting up his other pitches to RHB. But compare this to his numbers on decisive pitches:
Jimenez was having trouble putting RHB away with his slider in the second half as his k-rate dropped while opponents batting average and slugging increased. What's perplexing his how his location of the pitch changed in the second half.
In the first half of the season, Ubaldo's slider was over the plate frequently. He apparently got away with this. However, in the second half, he kept the ball away and it got hammered. The only explanation I can think of is that righty batters were fooled more often in the first half and began to adjust in the second. Jimenez tried to keep the slider away, however batters seemed to recognize it easier. There is some evidence to support this as RHB swung and missed at his slider 36.2% in the first half. However, in the second half, that number dropped to 28.6%. Right-handed batters simply recognized his slider better as the season progressed and Jimenez was unable to make the proper adjustments.