The John Dewan Rule

Ask any Saberist what they think about spring training, and you are likely to get the same answer across the board: “It’s meaningless.” And they’re right, almost entirely. Spring training really is a breeding ground for bad analysis for a multitude of reasons, most importantly the small sample sizes. Jimmy Rollins is currently the Phillies’ leader with 59 at-bats. As Eric Seidman listed here, the only two stats that become reliable between 50 and 100 trips to the plate are swing and contact rates.

When you break Rollins’ 59 AB down further, you find that he is not exactly facing premier Major League talent through and through. He is facing #5 starters vying for a job, middle-rotation guys working on a new pitch, and even Triple-A filler*. Sure, he faces the Jon Lesters of the world too, but those at-bats are not the overwhelming majority. Hitters are always tweaking things as well, such as the openness of their stance, their proximity to home plate, or the height of their hands prior to a swing a la Domonic Brown.

* Also known as the Yankees’ #3 starter. Boom! Roasted!

There is, however, one way to use spring training stats to get a general feel of the upcoming season. John Dewan was one of the few to foresee the breakout of Jose Bautista, who went from a previous career high 16 home runs to 54 last year.

How did he do it? By comparing hitters’ spring training slugging percentages to their career average slugging percentage. If the difference is 200 points or greater in favor of spring training, then the hitter has a 60 percent chance of a breakout season.

Here are the leaders in slugging percentage among Phillies with 35 or more AB this spring:

Player Pos AB SLG Car Avg DIFF
Pete Orr 2B 38 .553 .335 .218
Wilson Valdez 3B 47 .532 .326 .206
Ben Francisco OF 52 .635 .446 .189
Shane Victorino OF 51 .588 .428 .160
Ross Gload 1B 45 .533 .414 .119
John Mayberry OF 54 .630 .536 .094
Michael Martinez OF 54 .444 .368 .076
Josh Barfield 2B 40 .450 .375 .075
Ryan Howard 1B 51 .627 .572 .055
Raul Ibanez OF 51 .510 .476 .034

According to this theory, both Orr and Valdez are primed for breakout years, with Francisco on the cusp. Maybe the Phillies didn’t need Luis Castillo after all.

Obviously, apply extreme skepticism with this theory, but it’s fun to think about and it will be interesting to look back after the season to see how well it performed.


Crashburn Alley has advanced to the Sweet 16 in The Phield. The next match-up is against Recliner GM. With your help, Crashburn can advance to the Elite Eight, and hopefully win the whole damn thing.

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  1. Brian

    March 23, 2011 10:08 AM

    Nooooo, you’ve discovered my super-sleeper fantasy pick, Pete Orr!

  2. Shawn

    March 23, 2011 10:12 AM

    Pete Orr facts: 335 career avg SLG, has a strong opinion of public transportation.


  3. Sloth

    March 23, 2011 10:18 AM

    Haha I loved that Yankees joke in there, good job as always.

    I think the theory is interesting personally, I will be sure to look back on it.

  4. dejesus54

    March 23, 2011 10:18 AM

    Pete Orr has a 100% chance of being the Phillies’ best Canadian position player since Matt Stairs.

    (I originally wrote “best Canadian player,” but forgot Mathieson is from Vancouver.)

  5. Dan

    March 23, 2011 10:59 AM

    If Orr hits a home run off Jonathan Broxton in the NLCS this year, I’ll remember that I heard it here first.

  6. Aadam Aziz Ansari

    March 23, 2011 11:31 AM

    Small quibble with your second to last paragraph. Orr and Valdez aren’t primed to have breakout years according to Dewan’s analysis, only that they each have a 60% chance of such a year. Small but important distinction.

    I’d be interested to know if there is a similar effect in the opposite direction. IE, if a player significantly underperforms their career SLG in spring training, does that correlate with a down year? If not, this just may be a fluky coincidence.

  7. Aadam Aziz Ansari

    March 23, 2011 11:32 AM

    “You must play in a 36-team NL-only league.”


  8. FanSince09

    March 23, 2011 12:42 PM

    Wilson Valdez is good enough to start for just about any team in baseball

  9. Jay B

    March 23, 2011 01:10 PM

    Good stuff, Bill.

    Can’t wait for Valdez to Bautista MLB this year.

  10. Brian

    March 23, 2011 01:46 PM

    “You must play in a 36-team NL-only league.”

    That killed me.

    In all seriousness, it’s an NL-east-only league.

  11. Rob

    March 23, 2011 06:25 PM

    This is a good time to point out that Roy Halladay is slugging .210 above his career level!

  12. Josh B

    March 23, 2011 09:18 PM

    Is it just me or does Ben Francisco have that 2008 Jayson Werth feel to him? A late 20’s outfielder who could put it all together if he just gets enough AB’s… (overly optimistic).

  13. Scott G

    March 24, 2011 06:16 AM

    Not saying Francisco can’t be a good everyday player for us, but Werth WAS a 1st round pick. I feel like you’d almost expect him to be pretty good, breaking his wrist really set his progress back IMO.

  14. sean

    March 24, 2011 09:20 AM

    agreed with scott G Werth had the talent to be what he is. ben fran can be a really good platoon guy but as far as a regular everyday guy, not as sure

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