Looking at Felipe Rivero’s Other Offering: The Slider

Felipe Rivero has established himself as one of the games best left-handed relievers, with his 100 mile per hour fastball, and devastating changeup that creates swing and misses.  However, his slider is just as devastating of a pitch.

On the season, Felipe Rivero has a 0.86 ERA (a 20 ERA-, which adjusts for league and park) in 42 innings.  Among qualified relief pitchers (171 relievers), Rivero ranks third in ERA-, behind only Pat Neshek and Kenley Janson (19).  ERA for relievers is flawed, as it is only a small sample and they can give up runs that are credited to another pitcher.  In FIP – controlling for the three true outcomes of home runs, walks, and strikeouts, things said the pitcher can control – Felipe Rivero ranks 20th, and has a park adjusted FIP- of 58, which ranks 25th.  Furthermore, in DRA – a Baseball Prospectus measure that factors in multiple variables and is more predictable and reliable year-to-year than FIP – Rivero ranks tenth among all pitchers with at least 30 innings, as does his DRA-.

Felipe Rivero has been an excellent pitcher on the year.  He is striking out 28.9 percent of hitters, just walking 6.3 percent of batters, and getting swinging strikes 15.5 percent of the time, ranking 21st of the 171 qualified relievers.  At the beginning of the month, Travis Sawchik of Fangraphs wrote about how Felipe Rivero is nearing an elite level.

Sawchik detailed his pitches, citing that one way Rivero can get even better is by increasing the changeup.  Rivero’s run value on the pitch is at 3.0, and in fact he has three pitches at 3.0 or better.  His fastball ranks 14th, his changeup ranks 10th, and his slider ranks 25th in fangraphs run values.  He has a three pitch mix, and with his fastball and changeup being written about a lot, let’s focus on the slider.

Rivero only throws his slider 18.74 percent of the time, which ranks 43rd among left-handed pitchers with at least 250 total pitches thrown.  Rivero’s slider is just averaging 83.81 miles per hour, ranking 36th of 68 left handed pitchers to throw at least 50.  However, the vertical break the pitch gets is third highest, breaking 6.86 inches glove side.  The vertical movement on the pitch is at -0.23, which ranks middle of the pack.  It’s the glove side movement with velocity that makes the pitch the pitch that it is.

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Felipe Rivero’s slider ranks ninth best in wOBA among 177 pitchers with 30 or more at bats ending with a slider, with a wOBA of .139.  His expected wOBA, which uses launch angles and exit velocity, ranks 11th at .163.  The pitch generates ground balls, as Rivero ranks 15th among the 68 left handed pitchers with 50 or more sliders in ground balls per ball in play (57 percent).

Rivero’s changeup and fastball have been excellent.  The slider gives him a third weapon that allows him to get hitters out and be the elite pitcher that the numbers indicate that he is.

*Numbers from baseball savant, fangraphs, and baseball prospectus