Review of "The Baseball Economist"
I reviewed J. C. Bradbury's "The Baseball Economist" over at "The Griddle." Comments welcome here or there.
Labels: baseball
posted by Phil Birnbaum @ 4/18/2007 09:53:00 AM
17 comments
17 Comments:
Great review Phil -- as incisive and as interesting as ever.
I do think that Sabermetricians with an economics background tend to overuse (and sometime misinterpret) regression (Wages of Wins for instance). It seems that JC uses a lot of regression here. Any issue with any of the interpretation as far as you see?
To be honest I will probably wait for the paperback version
Beamer
Hi, Beamer,
Re: the paperback, isn't that what you said about Wages of Wins? :)
Most of the regressions give only the briefest description of how the regression worked, so it's hard to evaluate the intrepretation. For instance, in the Leo Mazzone chapter, JC writes that when trying to predict a pitcher's single-season performance, he considers:
age, team defense (DER), park factor, league ERA, career ERA, whether or not he's a starter, and whether Mazzone is the coach.
That's all we get. All seems reasonable, but I guess you don't really know for sure.
Phil
You have a good memory! Actually, after all you posts about WoW I actually took the plunge and went hardback.
Perhaps I'll do the same with JC's book but I have too many hardbacks sitting around! Too heavy.
I'vre always been slightly skeptical about the Mazzone work. I can't remember the numbers off the top of my head but if he is edging staff ERA down by 0.5 that, over 162 times 9 innings is a lot of wins. He should be paid a fortune!! Also why would hurlers revert back to their old ways after they leave Mazzone. Sounds implausable ...
Anyway, great review -- love what you're doing at this site.
Beamer
I have the same reservations about Mazzone, but since I haven't looked at it enough to come up with an alternative theory of what's going on, I really don't have anything more than a gut feeling. I certainly don't have any evidence to contribute to the discussion.
And I think the numbers in the book (and in the presentation at the SABR convention a couple of years ago) are accurate. It's a question of coming up with another theory of what happened there.
Do you have any ideas?
I can't remember the numbers off the top of my head but if he is edging staff ERA down by 0.5 that, over 162 times 9 innings is a lot of wins. He should be paid a fortune!! Also why would hurlers revert back to their old ways after they leave Mazzone. Sounds implausable ...
My answer: coaching's not a simple mechanical process of telling & teaching a person how to pitch, but more often an ongoing process. Constantly looking after mechanics, checking the video, putting them on a training program (the Cox/Mazzone Braves had their starters toss on the side twice between starts when all other teams only did it once), and perhaps most importantly of all keeping the pitcher mentally/pyschologically focused.
It might sound implausible to say that coaching has that big an impact, but the numbers on pitchers improving when playing for the Braves is real. It also sounds implausible to say that a series of pitchers all improving themselves upon arrival in Atlanta and getting worse upon leaving over a 15 year period is just a fluke. Something happened.
Personally, the only problem I have with that theory is the notion that all credit goes to Mazzone. Sorting out coaching credit is an incredibly difficult process & can never be done as well statistically as we'd like, because ultimately it revolves around relationships - how the coach relates to the pitchers, how acceptable they are to what he says. Also, how the coach relates to the manager & how that plays out. Mazzone developed Smoltz & Glavine, and got Maddux on board with his program. That gave him a tremendous amount of authority in dealing with the up-and-coming prospects and the rented out free agents. Put him on a team with a bunch of established pitchers, some veterans already eith their own established ways, and it may not go down the same way.
Chris J.
If the Braves really believe that Mazzone had that much of an influence, they would pay him commensurately. They do not do this. Getting 0.05 wins per game is worth 0.20 million$ per game on the open market. That's 32 million$ if even can influence all his pitchers at 0.50 per game. Every year. He'd be Albert Pujols.
On the other hand, football head coaches are paid at star-level prices.
So, either the Braves don't really believe they had Pujols, or they were accepting that everyone in MLB has a certain cap on pitching coaches that they have to respect, even though they let Pujols go.
I agree with Chris that the situation might be specific to the Braves staff. And Tom makes a good point that if the Braves thought he was worth 8 games a year, they wouldn't have let him go.
But why DID they let him go? It couldn't have been just money, could it? Because even if only 20% of the staff difference is him, he's still worth a lot.
I've always been skeptical about the Mazzone study, both because of the implausible magnitude of the impact (.6 runs/game) and the fact that pitchers apparently retain none of what he teaches them. It's been a while since I looked at this, but I recall wondering about these issues:
1) Selection bias: the Braves in this period had a great pitching staff and considerable financial resources. If a pitcher arrived and pitched as well or better than expected, they would keep him; if not, they had the ability to discard him and try someone else. (Most teams of course can’t do this.) And related to this is the possibility that Braves' management was very adept at obtaining pitchers likely to perform better than their past record, and releasing those likely to underperform.
2) Age control—I don’t think you can just including age and age^2 in a regression and say you’ve effectively controled for age. This small pool of pitchers may not have a typical aging pattern.
3) The fielding and league coefficients both understate (in runs) what we know are the actual impact of those variables. So Mazzone gets some credit for what the Braves' fielders do, and just being in the NL.
And, of course, we're not picking this coach and time period at random. This was an extremely successful pitching staff. If we looked at other great pitching staffs in history, would we find that those pitchers performed better than they did before and after those years? I think we might.
Guy, are you looking at a more detailed version of the study than what's in the book? Is it online?
As I said I haven't looked in depth at the studies so this is all rather speculative but I'd have a few questions ...
Did JC control for age improvement/decline in his numbers? Is the park factor biased (we all know that park factors have limitations)? If a pitcher's ERA improves in one season is it statistically significant on a pitcher by pitcher basis -- not for the whole collective? What about the influence of the generally great pitching staff? Is it possibly by pitching along side Smoltz, Glavine and Maddux at the peak of their powers that hurlers could raise their game? Perhaps it wasn't Mazzone at all but something around club ethos/environment? Did hitters also show an improvement when coming to Turner Field? Which pitchers showed the improvement? Was it across the board or just starters, or just relievers?
If I had to guess I reckon it is 50% luck, 35% club/team environment (created by Cox/JS) and 15% Mazzone ....
I also need to look at JC's work in more detail
Guy -- sorry to repeat quite a bit of what you said ... I was going to post a few hours ago but kid was vomiting and I didn't refresh the page
Phil/John: JCB did two earlier studies that are online. The second is at: http://baseballanalysts.com/archives/2005/03/the_mazzone_eff_1.php, and there's a link there to the first study.
Guy, I can't find the link to the first study ... the link to it in the second study is broken. Is it somewhere else?
Just read the Mazzone study -- interesting for sure.
Has JC controlled for park? It's doesn't look like it unless I am misreading the study. The regression contains the following variables:
-age,
-the run environment of the league, -the career quality of the pitcher, -the defense behind the pitcher
To me that seems to fail to control for park -- and we know atlanta is a pitcher's park.
JC's age adjustment puts peak age performance around 30-31 ... seems a little late perhaps, but not crazy.
For starters peak age is later at around 32 ... for relievers it is back to 31 again.
Beamer
John:
While getting peak correct is important, I think the magnitude of change is even more important. Otherwise, the post-Atlanta decline of Maddux and Glavine (for example) will appear to demonstrate the "Mazzone effect" when it really illustrates only the "it's tough playing baseball at 39 effect."
I posted this comment over at The Book blog, based on the regression in JCB's original article at Baseball Analysts:
Consider these coefficients for starters:
League ERA: .271
Team DER: -5.554
This means that if a pitcher leaves Mazzone and goes to the AL, where the ERA was usually 0.50 higher, the model only “expects” his ERA to rise by 0.135. And if Atlanta has a team DER of .720, and a pitcher leaves Atlanta for a .700 team, the model expects his ERA to rise by only 0.11, when in fact 2 points of DER translates into about .5 runs/game. So two major advantages for Mazzone pitchers in this period—pitching in the NL, and in front of a good defense—are not fully compensated for. (Now, I gather the latest analysis focuses on Ks and HRs, which obviously are not defense dependent. But you still need to deal with league, and park effect on HRs and Ks.)
Also, the career ERA coefficient is just .62, so the model will tend to somewhat underestimate great pitchers (i.e. predict too high an ERA), and overestimate lousy pitchers. This will be true in both Mazzone and non-Mazzone years, of course, but to the extent the good pitchers in this sample pitched more years with the Braves, it will again create an illusion that pitching for Mazzone reduces ERA.
I’d like to see the K-rates and HR-rates for these pitchers, league/park-adjusted and age-adjusted, with and without Mazzone. I’d have more faith in that than these regressions.
[NOTE: JCB does say in the article he is looking at park-adjusted ERA.]
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