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Carleton: Fact or fiction, the 'Verducci Effect'

From Russell Carleton at Baseball Prospectus on January 28, 2013:

Last week, Sports Illustrated writer and Jason Parks man-crush Tom Verducci put out his annual column warning about a specific type of player: A young pitcher (25 or younger) who saw a significant increase in his workload in the previous season over the season before that (defined as an increase of at least 30 innings, including postseason and minor-league work). Verducci claims that this sort of pitcher is in danger of either a significant injury and/or a performance decline in 2013 because his 2012 was much busier than his 2011. It's a proposition that's become known as the Verducci Effect.

Let's start with the positive: This is a perfectly reasonable hypothesis. It makes sense intuitively. If you are training to run a marathon, you don't go from maxing out at one mile to maxing out at 10 in a week. You have to build up your endurance along the way. Rick Peterson, who has been a pitching coach for several teams, has given the Verducci Effect his imprimatur. There have been several cases fitting the criteria in which pitchers have gone on to suffer major injuries or major declines in performance. We have face validity through imperfect analogy, expert testimony, and case examples. It's not silly to believe that Verducci's hypothesis could be true.

But, as someone who has taught both research methods and statistics, I see a few problems. None of those forms of evidence (analogy, testimony, or example) are legal tender as proof of anything. That's not how science works. If it were, Jenny McCarthy would be Surgeon General. Verducci himself states that the “25 or under, 30 or more” rule of thumb is "is not a scientific, predictive system." He's right. There are plenty of problems with how Verducci justifies his hypothesis. It might be minimally decent science to add the disclaimer, but it's irresponsible journalism. If you don't have good evidence for a theory, why write an article at a highly visible outlet and name names?

Read the full article here: http://www.baseballprospectus.com/article.php?articleid=19497

This page was last updated January 28, 2013 at 11:32 am MST.

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