After a hiatus of over four years, Jerome Williams is back in the majors. After coming up with the Giants as a 21-year-old in 2003, he’s bounced around to the Cubs, Nationals, Twins, Dodgers, and Athletics organizations, putting up unspectacular numbers. He also had a 2010 stint in Taiwan. The Angels brought him back to the U.S. before this season, and he had some success at Triple-A Salt Lake, posting a 4:1 K/BB ratio in 73 2/3 innings. He got the call to the major leagues last week, making a three-batter relief appearance on August 17th before being slotted into the rotation for a Sunday start against the Orioles. He impressed, allowing one run in seven innings while striking out six and walking nobody. Since his last appearance in the major leagues, he’s made some adjustments to his pitching style: first, he’s throwing harder. As Williams noted in a interesting post game interview with The Orange County Register’s Sam Miller, he used to conserve his fastball velocity but now prefers to go right after hitters. Consider the velocities for his different pitch types:
-------------------------+-------------------------+-------------------------+
| Pitch | 2007 | 2011 |
-------------------------+-------------------------+-------------------------+
|Two-Seam Fastball | 89.4 | 91.5 |
|Four-Seam Fastball | 88.7 | 91.5 |
|Slider/Cutter | 84.6 | 87.9 |
|Changeup | 82.2 | 83.5 |
|Curveball | 78.0 | 79.1 |
-------------------------+-------------------------+-------------------------+
It’s important to note that we have extremely little PITCHf/x data on Williams from before his 2011 return – in fact, there’s just one 2007 start (that was the first year with any regular season f/x data) at which we can look pitch by pitch, so, basically, we’re just comparing one 2007 start to one 2011 start. Not my favorite thing to do, but it’s necessary when the samples are so small.
Essentially, he’s throwing his fastballs ~2 mph faster, his change and curve ~1 mph faster, and his slider more than 3 mph faster. According to his interview with Miller, he started tightening up his slider in 2009 and he nows thinks of it as a cutter.
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