2012 PECOTA

[southsider2k5]

Much more at link

 

http://www.baseballprospectus.com/article....articleid=15992

 

  Quote

BP’s projection system, at its core, follows the same basic principles as it has before. We begin with our baseline projections, which start with a weighted average of past performance, with decreasing emphasis placed on seasons further removed from the season being projected. Then that performance is regressed to the mean. After that, we use the baseline forecast to find comparable players (while also taking into account things like position and body type) and use those to account for the effects of aging on performance.

 

Every season we put PECOTA under the knife, looking for things we can improve to make sure we’re coming up with the best forecasts possible. Sometimes what we come up with is a minor tweak. At other times, though, what we unearth is not only more significant, but an interesting baseball insight in its own right, even aside from its inclusion in PECOTA.

 

This season, we’ve made some rather radical changes to how we handle the weighted averages for the PECOTA baselines—we still deemphasize past seasons, but nowhere near as much as we used to. With such a dramatic and counterintuitive change, we thought it best to give our users an explanation of what was changed and why so that they could correctly use and interpret the PECOTA forecasts.

 

Last year, I was asked to appear on a Chicago sports talk station to discuss the town’s two teams, in particular how PECOTA saw them faring. I said many things, most of which don’t bear repeating (or for that matter remembering) this far past, but there was one thing I remember saying, and it probably does bear repeating—I expected Adam Dunn to be the best hitter on the White Sox in 2011. Suffice it to say, this statement does not represent my finest hour as a baseball analyst. Consequently, I’ve spent a bit of time thinking about Adam Dunn and whether there was anything in 2010 or earlier that hinted he might be capable of a season like 2011. In other words, is there anything that I know now about forecasting in general that would allow me to predict what happened using only what I could reasonably have known about Adam Dunn before the start of the season? The conclusion I’ve come to is that no, there really wasn’t. What happened to Dunn was, in essence, unforeseeable given what we knew heading into last season. That’s the bane of forecasting—no matter what you do, reality in all its many variations is always going to be able to surprise you.

 

Now it’s time to predict 2012’s stats, and PECOTA has learned from its mistake. No longer does it declare Dunn the best hitter on the White Sox. It has been humbled, dropping Dunn… all the way to second place, behind Paul Konerko. This is partly due to the fact that the White Sox are not a very good hitting team as currently constituted, having traded away Carlos Quentin during the offseason, but part of it is because PECOTA sees a far greater chance of the Adam Dunn that mashed baseballs for the better part of a decade showing up next year than the putrid Adam Dunn the White Sox saw in his first season on the South Side.

 

Naturally, some of you are going to look at PECOTA’s forecast for Dunn, think back to his abysmal season, and say, “I’ll take the under, thanks.” But PECOTA knows about his terrible performance just as we do; at its core, PECOTA takes past baseball statistics and applies a set of rules to them to come up with an estimate of what a player’s future statistics will be. If PECOTA is too optimistic about Adam Dunn, the culprit can be found in the rules governing the amount of emphasis to be placed on recent performance.

[winninguglyin83]

i'll take the under without another thought.

[mumbles3k]

Perhaps I put too much stock in sabermetrics, but this gives me hope.

[Andrew]

The under on what? Last year? Or the projection of being #2 behind KING?

 

Shouldn't be difficult to better the former, and beating the latter ain't sayin alot.....

 

I mean....out produce.....Alexei?

 

That's probably the only competition.

 

God, this team sucks.

Edited February 9, 2012 by Andrew

[Andrew]

Nobody disagrees, I guess....