THE BOOK--Playing The Percentages In Baseball

Kevin’s article prompted a short rant from me on the Phillies blog I write for.  Don’t get me wrong, Kevin is my favorite writer for BPro and I generally like all of them to some degree.  But there are just way too many articles on the interwebs that observe a projection and then make little to no effort to interpret it. Sure the historical comparables are a nice touch, but even that was just a database query.  Kevin has expert knowledge, I want to see him use it.

The combination of beautiful Minnesota weather and being cramped in a windowless office for 9 hours has made me short tempered.

The 90th and 10th percentiles for an established HR hitter is 40 and 20 HR.

I don’t know what you’d expect Kevin to do other than say that Heyward’s forecasts are 40 and 10.  I’m disappointed that PECOTA gives the 80/20 numbers as 22/12.  That’s ridiculously tight.

My point that I didn’t make is that the focus should be a little bit of numeric window dressing and alot of back story.

Exactly, as I said in my rant, using a projection in a post is useful, but I also expect the author to interpret it in some way. I’m of the opinion that a statline by itself is meaningless without interpretation.  Kevin may think that quoting the percentiles counts as interpretation but I’d much rather see that space filled with a scouting anecdote.  Anyway, aren’t the PECOTA percentiles empirically shown to correlate poorly with reality?

I guess this simply reflects my preferences and beliefs.  I firmly believe that an effective analysis uses stats AND scouting especially when both types of information are readily available.  Kevin’s article is all stats so it comes off to me as an ineffective and uninteresting article.

The 20-80% forecasts from PECOTA just don’t seem right to me, and they never have, even back in the day when I believed in the 50% forecasts.

There has to be at least a 20% chance that Heyward washes out and gets sent back to the minors, gets a minor nagging injury and struggles, etc., doesn’t there?  In which case he’s not going to be racking up 12 home runs and a .265/.334/.425 batting line.  I always felt there was more downside for most players than PECOTA projected.

I don’t have an explanation for why they come up with fairly optimistic batting average numbers (.300) for his 80th percentile--seems about right to me--but pretty conservative home run numbers for the 80th percentile.