Boston Red Sox’ Joe Kelly Should Abandon His Sinker

Regardless of the fact that we’re more than halfway through August in this disastrous season for the Boston Red Sox, I keep searching for positive signs for the future. Last Friday’s start for Joe Kelly was one of those hints of hope. In fact, all three of his August starts before tonight’s have been productive. He’s gone 3-0 with a 4.41 ERA (by far his best month this season, sadly) in 16.1 innings. Let’s take a look at some highlights of his start last Friday (including Mookie Betts being his usual magical self).

On first glance, you’ll notice that he was doing a fantastic job of keeping the ball down. It doesn’t take an expert to notice this, we hear commentators and pitching coaches and managers puke that phrase out 50 times a day during the season. For a pitcher who throws a lot of innings at Fenway and is prone to fly balls (31.9% on the season and a tick up to 32.7% at Fenway), it’s an important thing to remember and put into game action.

According to Brooks Baseball, Kelly’s sinker, which he has used as his primary pitch – 51.46% of pitches thrown in his career – is, “blazing fast, results in somewhat more flyballs compared to other pitchers’ sinkers.” That got me to wondering if there was any correlation to less reliance on the sinker and some consistency in his success. In the graph forthcoming below, you can see that from 2012 to 2014, Kelly has never thrown the sinker less than 44.3% of the time. This season, he has vacillated wildly with usage of the pitch. His two worst months, May and July, correlate with his two highest rates of throwing the sinker at 50.63% and 56.33%, respectively.



On the other hand, here in August he’s thrown the pitch 8.11% of the time!! Now, I’m aware that just changing the usage of one pitch, or nearly abandoning it from your repertoire, cannot be the sole correlative of performance change. It could, however, be something for Kelly and Carl Willis to inspect and tinker with.

One other thing that grabbed my attention is the increase in use of his slider and change on the season. Graphically, they are both an almost true uphill trend for 2015, topping out at 21.28% for the slider and 14.86% changeups. While that is only a slight up-tick in changeup usage from his career 12.04% thrown, it is a huge difference for the slider. Kelly has thrown the slider 10.33% of the time in his career. Maybe he’s found it to be a more effective and reliable tool.

If you go back to the video, you’ll see that three of his six strikeouts came via the slider. In order the strikeouts came on a change, slider, four-seam fastball, change, slider, slider. Not a single one on a sinker.

I wonder how many voicemail messages Kelly has received since May 7th from Juan Nieves telling him to junk the sinker?

One Response

  1. Gabriel D. Bogart

    During tonight’s NESN broadcast, Don Orsillo and Jerry Remy made mention of the fact that Kelly was utilizing his ‘secondary pitches’ significantly more in the last month or so and looking to it as a factor in his increased success on the mound.


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