Tuesday, July 23, 2013

Jeremy Guthrie and the Value of Defense

           Jeremy Guthrie seems to be an interesting person. His Twitter feed is often full of shoe giveaways and other assorted things. As a baseball player, and from a statistical perspective, he is equally interesting. Throughout his career, he has maintained a below-average K% and yet has remained an effective “innings eater”*. He doesn’t generate ground balls more than other pitchers, and he doesn’t strand more baserunners than other pitchers. He is roughly average in those categories. However, he does have a below average (or above average, depending on your perspective) career BABIP; essentially, fewer balls in play go for base hits against Guthrie than the league average, which is odd because the vast majority of pitchers have little to no control over their BABIPs.

*Innings eaters. A nice way of saying, “You’re not very good, but you’re not bad, and you’re healthy, which is valuable”

            I’m not entirely sure why in years past he has been able to maintain a low BABIP, but I’m going to focus on 2013 and talk about Fielding Independent Pitching, or FIP. FIP is an attempt to quantify runs allowed based on things the pitcher can control-strikeouts, walks, and home runs. FIP uses a league average BABIP and is placed on the same scale as ERA for comparison purposes. Jeremy Guthrie’s ERA this season is 4.41; an ERA quite becoming of an innings eater. However, his FIP is 5.50. His FIP is basically saying that he should be giving up a full run more per 9 innings than he actually is. Historically, Guthrie’s ERA is lower than his FIP; however, the difference between his ERA and his FIP is bigger in 2013 than any other year.

            There are a few reasons for his very high FIP. #1-the lowest K% of his career as a starter. #2-the highest BB% of his career as a starter. #3-the highest HR/FB% of his career as a starter. So, why is the difference so large this year? The Royals’ defense is the answer*. The Royals defense as evaluated by scouts and by advanced defensive metrics is one of the best defenses in the entire league, if not the best. The excellent Royals defense is ensuring that Guthrie’s BABIP remains low despite more contact against him this year. The Royals defense is ensuring that the extra baserunners are being stranded at a higher rate than in Guthrie’s past. Because elements outside of Guthrie’s control are keeping his runs allowed low, his FIP is higher than his ERA. As long as the Royals defense is strong, Guthrie will be acceptable. However, if the Royals defense declines, Guthrie will suffer a parallel decline.

Embrace the luck. Guthrie is more valuable to the Royals than any other team, which is probably why the Royals are paying him more than any other team would.

*As an aside, to those who are interested, I ran a regression analysis with the difference between team ERA and team FIP as the outcome variable and FanGraphs’ team Fld stat as the input variable. With only 1 variable, the R^2 of the model was 0.20, which means that the variation in defense as measured by that Fld stat explains 20% of the variation in the difference between ERA and FIP. Defense isn’t the only reason why FIP and ERA can differ, but it seems to be an important reason. I used only 2013 data for this analysis, so it is not very robust.

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