Bullpen Profile: Boston Red Sox Setup Man Koji Uehara

The game of baseball can be won or lost in the seventh or eight innings, so it is important to have a stellar bullpen. A crazy fastball-slider combo or a funky delivery can do the trick.  Ian York uses PITCHf/x to break down Boston Red Sox setup man Koji Uehara.

After Bartolo Colon and R. A. Dickey, Koji Uehara at 41 years old is the third-oldest active pitcher in the majors. Uehara has been a superb pitcher for the Red Sox, starting from his unearthly 2013 season, but the fractured wrist that truncated his 2015 season threw some doubt on his ability to bounce back and return to excellence in 2016.

He has gotten off to an excellent start this season: seven innings pitched, two hits, no runs, and six strikeouts against one walk, albeit (with the addition of Craig Kimbrel to the Red Sox) as an 8th-inning setup man rather than closer. However, not many 41-year-old pitchers have been effective, and it is worth asking if there are any caution flags on Uehara so far.

There is one flag that raises some concern. His velocity has dropped each year since 2013; his fastball this year averages just 87.0-mph, down nearly 3-mph from his 2013 average of 89.8-mph. In previous years, Koji’s velocity has started off slow and then trended upward, so at the end of 2016 his average will probably be higher than 87.0-mph. The horizontal line in these charts shows the season average velocity for his fastball and splitter, compared to the game-by-game speeds:

Uehara has never relied on blazing velocity, but 87-mph is a slow fastball. Considering pitchers who have thrown at least 20 fastballs this year (and therefore ruling out knuckleballers R.A. Dickey and Steven Wright as well as a handful of others), only Jered Weaver and Darren O’Day have averaged slower fastballs this year. Here is how Koji (the red dot) compares to all pitchers who have thrown at least 20 fastballs so far this year:

Uehara has always had exceptional spin rate on his fastball. High spin rate on a fastball makes it “rise” more relative to the path it would follow according to gravity alone, so that high-spin fastballs tend to be more deceptive and harder to hit. Uehara’s spin rate has held up relatively well, but is also down from some of his previous years (2397 RPM average in 2016, from a peak of 2515 RPM in 2014; but very similar to last year’s 2403.)

Velocity and movement are important, but Uehara’s strength has alway been his extraordinary location and the confusion between his fastball and splitter. His location, so far, seems to be just as good as ever. Compare his pitch locations from his extraordinary 2013 (shown as a heat map here), to his locations so far this year (shown as circles overlaid on the heat maps):

The patterns are very much alike. Uehara’s splitter and fastball, which start off looking very similar, end up in quite different locations. He can precisely target the outside edge of the strike zone with his fastball (to right-handed batters) or his splitter (to lefties).

Location is the most important of a pitcher’s weapons, and Uehara seems to have maintained that weapon well. At some point, location will not overcome declining velocity, but so far, the evidence says that Uehara’s velocity is still high enough to fool batters. We can hope to see him baffling batters through this season, and perhaps for several more seasons to come.

Ian York uses the PITCHf/x to monitor the strike zone, highlights great performances, monitors league-wide trends and tracks the performances of some interesting young hitters.

Follow Ian on Twitter @iayork.

All data compiled from PITCHfx and Baseball-Reference.com.

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.

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