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What’s Going on With Jon Lester?

Yesterday, I was posed a question on Twitter: What’s going on with Jon Lester? I had some initial thoughts on the answer to that, but wanted to see if I could find the right data to back it up.

Lester has not been shy of tinkering around with his arsenal and this season has been no exception. Pitch f/x data shows that Lester is relying much more heavily on his sinking fastball than he has before. Now, one might assume that throwing more sinkers would result in more ground balls, but this has not been the case thus far. Lester’s ground ball rate was 50.5 percent last season and currently stands at 48.2 percent this season. While Lester is walking fewer batters, focusing more on location, and inducing weak contact, his strikeout rate is down and the contact hasn’t been as weak as planned. According to FanGraphs, his line drive rate against is at 23.2 percent, which is a far cry from the 16, 17, and 18 percent line drive rates allowed over the last three seasons.

Why the harder contact?

Though Lester is throwing more sinkers, that particular pitch is not as affective as it was over the previous couple of seasons. Looking at data from TexasLeaguers shows us some glaring differences between Lester’s sinker from the 508 times he has thrown it this season compared to the previous 500-plus times he threw it from 4/1/10 to mid June of 2011. Most notably, and probably the biggest issue in his lack of success so far this season, is the loss of vertical break in the pitch.

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Below is a side view where pitch f/x illustrates the difference…

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There has also been a huge difference in location of the pitch…

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You can see that not only has Lester’s sinker flattened out, but he’s catching much more of the middle of the plate with it this season.

Combined with the fact that Lester has been relying quite heavily on the sinker this season (30.5 percent), it seems that the two factors above can help explain why Lester has not only seen a drop in his strikeout rate, but also an increase in hard hit balls in play, resulting in a higher BABIP and line drive rate than he has experienced over the previous two seasons.

That being said, baseball is a game of adjustments and there is still an entire second half to come. Lester has shown the ability to be a very valuable fantasy starter in the past, so he can get there again if he adjusts accordingly.