For five years Joel Peralta was your typical middling major league reliever. Then in 2010 and to a greater extent in 2011, he became a dependable setup man that his team could rely on, even filling in at closer for the Rays when Kyle Farnsworth dealt with elbow problems in September. Is Joel Peralta now, at age 35 going on 36, really a dependable middle reliever?
The difference staggering. From 2005 to 2009, Peralta posted a 4.61 ERA and a 4.17 FIP, allowing a staggering 1.4 home runs per 9 innings as a recorded just 2 saves and 31 holds in 223 relief appearances. Then in 2010 and 2011 alone, he posted a 2.55 ERA and 3.19 FIP, allowing his homer rate to 0.9 per 9 as he recorded 6 saves and 28 holds in 110 relief appearances. What in the world happened in between 2009 and 2010 for Peralta? I don’t know about you, but my knee-jerk reaction is to check Pitch F/X. Due to the lack of data before 2008, we’ll compare Peralta’s 2008-2009 seasons with his 2010-2011 seasons using the Pitch F/X Data from Texas Leaguers.
Taking a look at this graph (which you can see a quick explanation for here– see the paragraph right under the similar-looking graph), you can see that Peralta stopped using his slider in favor of a splitter and overall his pitches moved quite a bit more. His fastball, curveball, and changeup were all more dynamic, and while his splitter didn’t move particularly well, it had some nice downward movement before landing in the catcher’s glove. That sharper movement along with the increased effectiveness from his splitter compared to his slider made Peralta a much better pitcher. Not only was he able to get more swings and misses based on his improved arsenal, 13% of his pitches in 2010-2011 compared to 10% from 2008-2009, a pretty big difference, but it also helped him limit the longballs and improved confidence in his pitches allowed him to throw a few more strikes as he improved his BB/9 from 3.0 to 2.1. Now, three years after Peralta changed his arsenal, hitters will have a more detailed scouting report on his pitches, and his pitches don’t exactly blow away hitters. Nevertheless, the improved movement on his pitches will help him be a pretty good reliever for at least 2012. Maybe his ERA will start looking more like his FIP (which came at 3.37 in 2011), but especially while pitching in a pitcher’s ballpark at Tropicana Field and with very good defense behind him, Peralta should continue to be productive for the short-term. Peralta is a good reliever and although middle relievers’ performance is very volatile, Joel Peralta seems like a relatively good bet to be a trustworthy reliever for Joe Maddon and the Rays in 2012.