Aviles and PrOPS

I thought about just adding a comment to the Aviles/Sickels thread, but as I think Mike Aviles will be the single most talked about person this off-season for RR, I wanted this to be a new post.


So, a lot of you read my look at xBABIP and the royals, but a central theme about some comments was what it really means. When comparing actual versus expected values, how does that translate to more traditional stats which actually tell you about on-field performance. i.e. what does a BABIP-xBABIP of .60 mean?

Enter PrOPS (I'm gonna call it props to save wear and tear on my shift key). Props is short for predictive OPS. It was developed by economist JC Bradbury a couple years ago. Basically, it takes a bunch of peripheral rate stats and turns them into a luck neutral, semi-park neutral OPS number. here is the article introducing it.

It seems the exact formula is proprietary as far as I can tell, I have tried to reverse engineer it and have a working version w/o park factors, but since THT
reports the stat, its easy to look up. Now, I really like the concept of this. Its not perfect, but as a normalizing agent, it is my favorite stat I have found to see true performance.

Props isn't necessarily a predictive stat. However, if you can forecast the components that make up the calculation, it can be used in a way. I might do a little of that over the off-season.


Now, I said this post was about Mike Aviles, but I'm gonna be really quick on his analysis.

2008 props:        .737

OPS - PrOPS =  .096

that .096 would be the largest difference of ANY qualified batter this year.

Is a 740 OPS bad for a middle infielder? no. Can he improve? sure, but here are the fundamental components of OPS, which ones do you think he gets better at for his age 28 2009 season? What about a year of bad luck or a sophomore slump?

  • Line drives per batted ball
  • Groundball-to-flyball ratio
  • Walk rate
  • Hit-by-pitch rate
  • Strikeout rate
  • Home run rate
  • Home park of the player

I have said this about a dozen times now, I hope Aviles proves me wrong, but the 2009 Mark Quinn award seems well within reach.

P.S. for good news. props like gordon, dejesus, and shealy



This FanPost was written by a member of the Royals Review community. It does not necessarily reflect the views of the editors and writers of this site.

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