Sean O’Sullivan Hopes To Impress Red Sox

The Boston Red Sox will kickoff their spring training on February 29 against Boston College and Northeastern University like they do every year. Although the games do not count in the standing for another five weeks, players are trying to earn valuable roster spots. Ian York looks at the starter of game two, Sean O’Sullivan.

Sean O’Sullivan, signed by the Red Sox to a minor-league contract for 2016, will start against Northeastern in the traditional college doubleheader that kicks off the spring training season. O’Sullivan, a right-handed pitcher, has played in a total of 66 major-league games in a six-year career that has seen him bounce back and forth between the minor leagues and four major-league teams – five, if he makes the Red Sox roster. His career numbers in the majors are less than mediocre, with a cumulative 5.95 ERA and 1.578 WHIP; his best year was in 2013, when he posted a 3.96 ERA for the San Diego Padres.

O’Sullivan throws a standard pitch repertoire of a four-seam fastball (called “FF” by PITCHf/x), sinker (“SI”), slider (“SL”), changeup (“CH”), and curve (“CU”). In his 13 games for Philadelphia last year, he did do a good job of mixing his offerings, with plenty of slider and changeup usage:

All of his pitches are slower than the average right-hander’s. His best pitch has been his changeup, but that is mostly by default, since his other pitches are all negatives.

The one parameter where O’Sullivan may be exceptional is in the amount of movement on his curve and (to a lesser extent) his slider. The vertical movement on his curve in 2015 was among the best among right-handed pitchers, and his slider was also among the leaders. These charts show the average vertical and horizontal movement among all right-handed pitchers in 2015, with O’Sullivan’s average shown in red:

In both cases, the break is at least partly a product of pitch speed, since his slow pitches have more time to break. Still, this is a little reminiscent of Rich Hill, last year. The Red Sox noted that his curve had outstanding spin and horizontal movement, and encouraged him to pitch to that strength.

It is unlikely that O’Sullivan will be remotely as successful as Hill was last summer. Most likely, if O’Sullivan breaks into a major-league starting roster this year, it will be because many things will have gone disastrously wrong with that staff. But he is a low-cost, low-risk gamble. It will be interesting to see how much he uses his curve and slider during spring training.

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

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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