Sunday, July 1, 2007

Misunderstanding "statheads"

Peter Abraham has a great blog, if you're a Yankee fan. As a beat writer for the Journal News, he has access to a lot of information that other fans do not. He uses his blog to publish this information almost instantaneously. If you want need up to the second Yankee information, there isn't a better source.

However, Mr. Abraham has this really bad habit of going out of his way to stick to "statheads" over their comments on his blog. I think this reflects a general habit among print media, particularly beat writers. Peter often responds to statistical criticism by referring to comments made by Yankee coaches or players. That's not too surprising. After all, it's his job to cover these people.

I do think that his criticism is generally misguided. For example, he's been on a crusade against people who supported more playing time for Josh Phelps recently. In his latest mailbag, he refers to to a recent correspondence with a fan who had the audacity to suggest that he knew more, through statistics, about Phelps' defense at first base than Don Mattingly, defensive first baseman extraordinaire in his day and now the Yankees' bench coach.

Here's what's interesting about the exhange: it really doesn't matter how good Don Mattingly thinks Josh Phelps is at first base. What matters is Phelps' performance at first base. Statistics are often an excellent starting point for measuring performance, because they tend to be more objective. If we had a statistics (and we don't) that perfectly measured first base defense, and it showed that Josh Phelps was adequate there, Don Mattingly would be wrong. It's that simple. Since this stat doesn't exist, we do weight Don Mattingly's opinion higher, since he may be capable of observing things that our imperfect stats cannot detect. However, this is also where scouting observations can be misleading: Josh Phelp's may look like complete trash as a first baseman, but that doesn't matter if he actually performs well there. This is the chief market inefficiency that Billy Beane was portrayed to have exploited in "Moneyball."

I'm not saying Phelps is a good first baseman. I suspect Mattingly is right; he probably isn't very good. The important thing to take away from this is that expert opinions cannot change objective truth. This is why it is important to always have some objective base for analysis and to know the limitations of this base. It allows you to put expert opinions in perspective. I would behoove Mr. Abraham to remember this when statheads start disagreeing with the baseball experts in the Yankee organization. No amount of expert hand waving can turn a poor player into a productive one or a productive player into a poor one. No matter how you slice it, it's very, very hard to imagine a world in which Miguel Cairo is more productive at first base than Josh Phelps. The objective evidence is too strongly in Phelps' corner.

It's not hard to see why beat writers like Mr. Abraham lean towards the opinions of men like Don Mattingly and Joe Torre. For starters, they are eminently qualified to speak on the topic of baseball from the perspective of a player and coach. However, and I think this is the key point, Mr. Abraham and others in his profession have a vested interest in promoting the opinions of these men. If we stopped caring about what Joe Torre or Don Mattingly thinks, Pete Abraham is out of a job. I don't think that beat writers intentionally promulgate opinions based on this pressure, but I do think that it surfaces subconsciously in their writing.

What's most aggravating about this anti-statistical bent is that it misunderstands the stathead position consistently. When I say that Alex Rodriguez has been 55.7 runs better than a replacement level player this year, as measured by VORP, this statement is unequivocally true. The question is whether or not VORP accurately measures what it purports to measure. Unfortunately, mainstream writers never tackle this question, instead choosing to throw quotes around from their subjects that have nothing to do with an objective evaluation of anyone's baseball playing ability.

If VORP is perfectly accurate, then it doesn't matter one iota what Joe Torre, Don Mattingly, Brian Cashman, or anyone else thinks about a player's performance. They will be right or wrong inasmuch as their opinions agreed with those inferred from the correct use of VORP. Since VORP isn't perfectly accurate, their opinions matter, but how much? If VORP is 99% correct, or 95% correct, or 90% correct, how much weight should a person's opinion be given? This question can only be answered by a thorough analysis and understanding of VORP and other tools of its ilk. For whatever reason, the print media has largely chosen to duck this issue altogether. Pity. I would absolutely love to read a well-reasoned, objective criticism of statistical tools like VORP.

I won't hold my breath.

4 comments:

die Amerikanerin said...

So, when using VORP, is the "replacement player" just an average, or is this statistic usually used with a specific replacement player in mind? Or does it get used both ways?

D.Cous. said...

John, John, John. You can't rely on cold statistics too heavily, because they don't tell you how HARD someone plays, or how much heart they put into the game.

Heh heh, sorry. While the above is true, stats don't tell you about a player's peculiar style of hitting the ball or whatever, just that he hits it frequently or infrequently, most people would find the latter information more useful in determining whether or not they should pay attention to the guy.

John Lynch said...

Ahem.

You will note that on the right side of the blog there is a list of statistics that I use with explanations. Some, like VORP, even have a link so that you can read about them in more detail.

That being said, VORP measures from a more or less arbitrary "replacement level" baseline. It isn't referring to a specific player, nor to the league average. Basically, "replacement level" is supposed to represent that guy who's too good to be in the minors, but not good enough to be in the majors. Measuring from this level is a good idea because every player in MLB should (by definition) better than replacement level.

The classic example of why this is important is as follows:

Take three players: Joe Average, Flash Hurtalot, and Jim Stiff. Every year, Joe gets 600 at bats and produces exactly zero runs above average. Flash only manages 100 at bats before getting hurt, but he manages to produce 10 runs above average in that time. Jim has to take Flash's place, so he gets 500 at bats in which he produces 25 runs below average.

Which player is the most valuable? Runs above average believes that Flash is the most valuable, but this is clearly wrong because someone has to take Flash's place when he gets hurt.

Runs above replacement would look more like this:

Joe Average: 30
Flash Hurtalot: 15
Jim Stiff: 0

This is a much more accurate picture of the individual players' value.

If you want to know someone's value above a specific player, that's easy to do with VORP. Just subtract player B's VORP from player A's VORP and you've got it.

die Amerikanerin said...

Ah, thank you.