After putting up a 4.39 ERA at the All Star break, Andy Pettitte wasn't necessarily disappointing on the mound, but he left room for improvement. Many fans still expected him to replicate his 2010 and 2012 this season. After an awful start against one of the leagues worst offenses (the White Sox), Pettitte reached a season high 4.71 ERA after going just 2.2 innings and giving up 11 hits, 1 walk, and 7 earned runs on August 5th. Since then, Pettitte has made some changes on the mound, resulting in 4 starts, totaling 24.0 innings where he allowed 23 hits, 9 walks, and just 2 earned runs. While it looks like he hasn't made much progression with strike outs, Pettitte has lowered his line drive rates and increased the amount of weak contact. From the naked eye, the lefty appears to possess more command and better movement since his implosion in Chicago, and last night we got a quote as to why he's seeing better results.
“I just feel like everything’s working for me,” Pettitte said. “My cutter’s working good, and I have a little bit better command, I feel like, of the outside corner. Just feeling better. My sinker is sinking now when I throw it. When you throw that out there and you’re able to get some groundball double plays again, that’s huge.”
“It obviously has to do with my arm slot and has to do with my hand position,” he said. “At my age, I didn't think I would ever lose that again, to tell you the truth, and I feel like I did.”
So let's take a look at his arm slot, at least in terms of PITCHf/x recorded release points. BrooksBaseball has the data and the scatter charts for his pre-arm slot change, and the latest 4 starts. If you click the links, you'll see what looks like a much tighter release zone in his most recent starts, and to better compare the two, I've copied the two release points over each other.
Above, the release points outlined in red are the average locations in his last 4 starts. It's very clear now that his arm slot is much more consistent with the rest of his repertoire. In terms of individual pitches, his changeup and four-seam release points are now significantly lower and uniform.
I suppose that it's possible that Pettitte was thus tipping his pitches, perhaps hitters saw the higher release points and identified the fastball. What's much more likely is that the change in movement and consistency has led to better control for the southpaw. According to BrooksBaseball, the horizontal movement on his four-seam has increased by nearly 4 inches in his last 4 starts, as well as nearly 2 inches on the sinker, followed by decreases on the cutter, curveball, and changeup. Likewise, the vertical movement systematically dropped around an inch on his fastballs and changeup.
Here are two four-seam fastballs thrown from the stretch by Pettitte. One of these pitches was thrown to Billy Butler on July 11th, and the other to J.P. Arencibia on August 22nd. You'll notice that the deliveries don't match up very well, and both disparities show up in his windup and stretch. Over the last 4 starts, the lefty is getting rid of the ball much quicker than he was previously, and you can see in the GIF that his shoulder and trunk rotation happens more rapidly in one of the two deliveries.
Delays in pitching mechanics can often lead to inconsistencies in timing and repetition. Now that Pettitte is using a more fluid motion, he is likely finding it easier to not only repeat his release point/arm slot, but he's finding a rhythm where he's less likely to over or under rotate his shoulders. At the root of all this, Pettitte is showing improvements in timing, repetition, and momentum.
While the lack of strike outs could be an understandable concern, Pettitte has a history of inducing weak contact when he's locating his pitches. The correlation between his mechanics and apparent control are enough for me to be confident in his recent small sample size of positive results.