David Brown/Spurdynasty On Fastball Velocity & Pitching Performance: Part II

In light of the warm reception that David Brown's (a.k.a. spurdynasty) last exhaustive piece on the connection between fastball velocity and starting pitching performance received around these parts, I decided that it would be a bit of a shame if the reliever-oriented extension of that original piece was lost in the rumor-mongering fray, so included below is a brief excerpt from what I like to call Part II:

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FanGraphs was used to capture the Pitch f/x data for all relief pitchers who logged at least 50 innings in 2008. The pitchers were sorted based upon the average velocities of their fastballs. The rolling averages of the ERAs, FIPs (fielding-independent ERA), K/9 (strikeouts per nine innings), BAA (batting average against), HR/9 (home runs per nine innings) and LOB% (left on base percentage) for 10 relievers at a time were calculated and plotted, and are presented in the two graphs below. An explanation of rolling averages is provided at the bottom of the article:

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Unlike what was observed for starting pitchers, the various performance metrics of the relievers show very little correlation with fastball velocity outside of the top 15 or so relievers. Most surprising is the lack of an inflection point at average fastball velocities of 91 mph. With starting pitchers, a sharp decrease in performance is observed among pitchers whose fastball velocities average less than 91 mph (see below):

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Check out David's full piece here: http://www.bbtia.com/home/2009/7/28/effective-relievers-and-the-texas-rangers-bullpen.html

On tangentially related notes (since they are my co-writers and all), Trip Somers has dissected a recent New York Times piece by Mark Hyman (which cited a pair of studies that found no link between curveballs and pitching injuries), and in case you missed the FanShot, Jason Parks' debut album, entitled "The Bear Coat," drops next month. Check both out.