Pitching Repertoire of Joe Kelly

Joe Kelly was acquired by the Red Sox last season in the Allen “Wrench” Craig trade with the St. Louis Cardinals. The 26-year-old righthander has had mixed success in his three years in the majors. Having looked at Clay Buchholz, Rick Porcello, and Wade Miley, Ian York now looks at Kelly’s pitches.  

Kelly may be the most intriguing of all the 2015 Sox pitchers, with the best pure “stuff” of all the starters. His fastball averages about 96-mph with gusts up to 100, and his pitches often exhibit dramatic movement. This is reflected in his total base per pitch charts, which show a lot of intense blue, meaning that batters do very poorly against most of his pitches (as always, these charts are shown from the umpire’s point of view):


(FT-Two-Seam Fastball, CU-Curveball, FF-Four-seam Fastball, SI-Sinker, CH-Changeup)

Even though his pitches ‒ when thrown for strikes ‒ are very difficult to hit well, Kelly’s problem has been finding the strike zone. Sometimes he succeeds in getting batters to chase his pitches out of the zone ‒ especially his curve, where batters frequently swing at pitches below the bottom of the strike zone. However, he still throws lots of balls. Among the 156 pitchers who threw at least 90 innings in 2014, Kelly ranked 143rd for BB/9 at 3.92.

This shows up in the background of these charts ‒ the green contour maps that show the distribution of all of his pitches, balls and strikes. Many of his pitches show a distribution that extends well out of both the rulebook and de facto strike zones.

PITCHf/x identifies a two- and a four-seam fastball in Kelly’s repertoire. But the two blur together; both are fast and have significant movement. The slightly slower pitches with slightly more break may be two-seam fastballs, but there is no clear distinction.

For example, here is an animation of Kelly’s pitches to Jesse Hahn, in the second inning of a San Diego/St. Louis game on July 30, 2014. According to PITCHf/x, Kelly threw three two-seam and three four-seam fastballs. Two of the two-seamers move more than, and are slower than, the two four-seamers, but there isn’t much of a distinction between the two pitches.

Kelly has shown the potential to be a very good pitcher but 2015 will be his fourth year as a full-time major-league starter. It is time for his potential to become performance. Perhaps this is the year he will become as effective as his individual pitches suggest he can be.

Ian York visualizes baseball in a new, beautiful way, examining umpire strike zones, the repertoire of pitchers and the value of catcher framing.

Follow Ian on twitter @iayork. Follow us on twitter at @SOSHBaseball.

About Ian York 208 Articles
Ian is an immunologist and virologist who lives in Atlanta with his wife and two sons. Most of his time is spent driving his kids to baseball and soccer games, during which he indoctrinates his children on the glories of Pedro Martinez, the many virtues of the Montreal Expos, and other important information.

1 Comment

  1. This article is tremendous. It also has the potential to be tremendously frustrating in retrospect – if he never lives up to the caliber of his stuff.

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