Rajai Davis, Stolen Bases, and WPA

I've never seen stolen base WPA available to look up, but it's simple to sum up and calculate. And the results are interesting enough to play around with in several different ways.

  • Rajai Davis has a -1.47 WPA over this season, which means that he's cost the A's almost one and a half wins below an average player offensively. Remember that what separates WPA from other stats is that it's context-sensitive, which means that it takes situations and "clutchness" into account. Furthermore, if you add up only his positive contributions, you get 5.88 wins. His negative contributions come out to -7.35 wins. His WPA just from stolen bases and times caught stealing? 0.392. Stealing bases is a very, very minor part of a player's production, even for a blazingly fast speedster like Rajai Davis.
  • In fact, if you break down that WPA figure by event, you get the following chart. Even if he had never been caught once, his legs would have only contributed 0.68 wins.

Sbwpa_medium

  • We can calculate Rajai's break-even rate for steals, using his data from this season. Now, this is in no way a large enough sample to mean much, but it can be interesting nonetheless. If we only look at his 2010 steals and times caught going from 1B to 2B, the rate of successful steals needed to create a net positive effect is 74.6%. The usual quoted number? 75%.
  • And lastly, how good is Rajai at picking his spots? The win probability model has a stat built in called "Clutch", which compares performance that's context-sensitive to performance that's context-neutral (more information here). We can repurpose that stat and only look at WPA that comes from stolen bases. Instead of measuring clutchness, it would instead show whether a player is picking spots to steal that are more advantageous. Rajai's stolen base clutch score? A slightly negative -0.018. That's actually quite impressive, because it's obviously easier to steal when a successful stolen base wouldn't impact the game much. The fact that his stolen base clutch score is nearly positive means that he can almost take a base whenever he would like, even if the defense would very much rather he wouldn't. For contrast, Coco Crisp's stolen base clutch score is -0.072 with half as many stolen bases as Rajai.

New slugger Chris Carter and the A's attempt to get up off of the floor tonight at 7:10. We've got a matchup of two strong aces, Brett Anderson and Felix Hernandez.


Current Series

Mariners lead the series 1-0

Mon 08/09 WP: Doug Fister (4 - 8)
SV: David Aardsma
LP: Vin Mazzaro (6 - 4)
1 - 3 loss

Oakland Athletics
@ Seattle Mariners

Tuesday, Aug 10, 2010, 7:10 PM PDT
SAFECO Field

Brett Anderson vs Felix Hernandez

Partly cloudy. Winds blowing out to right field at 5-10 m.p.h. Game time temperature around 75.

Complete Coverage >

Wed 08/11 12:40 PM PDT

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