A couple days ago, in an article about prospect analysis in baseball (subscription required) Nate Silver produced a cool table showing the year to year correlations of the six major batting events. This morning while I wait for my dough to rise, I decided to replicate this analysis with my new found baseball hack ability.
Here's the result, showing the 2004 to 2005 correlations for rate-adjusted batting statistics for all players with more than 250 at-bats in both seasons:
Hits / PA 0.422 Singles / PA 0.663 Doubles / PA 0.369 Triples / PA 0.501 Home Runs / PA 0.702 Walks / PA 0.718 Strikeouts / PA 0.813 Plate appearances 0.405
What Silver was trying to show by presenting his table (which included all year to year correlations since World War II) is that "there's really no such thing as a doubles hitter."
You can see from looking at the table that there's very little relationship between how many doubles a hitter hit in 2004 and how many they got in 2005. But a home run hitter in one season is likely to hit them at the same rate in the next season. Also note that strikeouts and walks are very highly correlated. So, 2004 and 2005 strikeout leader Adam Dunn is likely to strike out more than 150 times in 2006. Thankfully for Reds fans, he'll probably also hit more than 40 home runs.
The last number is also interesting. There isn't a great correlation between plate appearances between seasons. This is probably a combination of older players breaking down between 2004 and 2005, and younger players stepping in to take their place at the plate.
Yesterday I discovered (and ordered!) a new book from O'Reilly called Baseball Hacks by Joseph Alder. I've got a bookshelf full of O'Reilly books on other computer subjects, so I'm very excited to see this. On the web site for the book, there are a couple example hacks from the book.
Last year I spent some time getting the Lahman database into MySQL so I could fool around with some advanced baseball statistics. The Lahman database is a Microsoft Access database, and doesn't allow re-distribution, so for an open-source advocate like me, this isn't exactly the best source for baseball information. It took me a few days to get it all into MySQL successfully, and any of my improvements couldn't be distributed.
Well from reading the sample hacks, I discovered there's a less restrictive database that's also available for MySQL (a free database server). In addition, the author of Baseball Hacks shows how to connect a MySQL database with the fantastic statistical package R. R is also free, and is incredibly powerful. I also found previous article by the same author. Some of what appears below is based on that article.
Anyway, I can't wait to get the book to see what's in it, but meantime I did a very simple analysis comparing payroll to wins for the 2005 season. For the 2005 season, team payroll numbers range from a low of $29.7 million for the Tampa Bay Devil Rays to the Yankee's astronomical payroll of $208.3 million. The second place team, the Red Sox, spent only $123.5 million on player payrolls in 2005. What does all that money buy? I'm sure the owners hope it'll buy them enough wins to make it to the playoffs, and hopefully win the World Series. The White Sox, winners in 2005, were 13th in payroll at $75.2 million.
It turns out that payroll doesn't really account for a lot of whether a team wins or loses. It explained only 24% of the variation in wins in 2005. For comparison, a team's hits and earned run average explains 72% of the variation in wins. Obviously, getting lots of hits, and keeping your opponent from scoring runs will contribute to winning a lot of games.
But what I want to see is whether a team did better than expected based on their player spending. The Yankees didn't wind up with the best record in baseball, despite spending more than twice as much as every other team in baseball except the Red Sox. How badly did they under-perform?
Not that badly, actually. The plot below shows the relationship between payroll and wins for 2005. The straight line is the regression line showing the best linear fit to the data. The team letters on the plot show how they actually performed. Teams that show up above the line, played better than their salaries would have predicted. Those below, did much worse.
For example, look how far the Chicago White Sox (CHA) are from the regression line. The Cardinals also wind up well above what we would expect based solely on their salaries (and that's with Scott Rolen on the DL the whole season!). Also check out the Cleveland Indians. They're a team that has a lot of very good younger players who aren't eligible for arbitration yet, but have loads of talent.
You can see the Yankees over on the right, far from all the other teams. Based on their payroll, they should have won 102 games in 2005, but only managed 95. The Kansas City Royals were much worse, only managing to win 56 games when their player salaries predicted 75 wins. It's easy to explain why teams like the Dodgers or Giants didn't do well in 2005---their high paid players were injured for most of the year---but something else must be going on with Seattle and Kansas City.
What does all this tell us about baseball? Well, I'd argue that this metric (payroll vs. wins) tells us something about how effective the front office of a team is. Smart general managers will pick up talent that is undervalued by the market, buying more wins than they're paying for. Also, teams with a good farm system can "grow their own" talent, rather than having to buy it on the free market. Teams like Cleveland and Oakland are good examples of this. The excesses of George Steinbrenner should have been enough to buy a World Series championship, but the Yankee front office overpaid for all their veteran talent, and in 2005, they didn't live up to their high salaries.
If you want to see the R code I used to generate the plot, you can download it from the link.
A couple days ago I mentioned Roy Eisenhardt, who was the President of the Oakland Athletics baseball team from 1981 - 1987. He was the subject of a 1983 Roger Angell Profile in The New Yorker.
When asked if he would make an expensive late-season trade for a star player if he thought it was
necessary to win a pennant that season he replied:
We want to be respectable and competitive, and we want to win our share of everything, including championships. But the way to do that is by being patient and foresighted. You can't just buy it or grab for it---we've already seen too much of that in the game, and its results. (see New York Yankees, 2005---CSS)
If the deal includes the transfer of good young players, it means you're just mortgaging your future for your present. Qualitatively, what's the worth of winning the whole thing versus the worth of being competitive each year? No one wants to accept second place, but unless you actually win the World Series you'll see yourself as having lost in the end.
The article was published in 1983 and shows remarkable foresight on the part of Eisenhardt. Recent research at Baseball Prospectus has attempted to quantify the value of a player to a team based on how many wins they'll add, and what effect that will have on the team's standings.
For example, if paying $27 million dollars for three years of Matt Morris yields an additional five wins over the course of the 2006 season, are those five wins enough to bump you into the playoffs, which is worth a lot of money to a team? For a rebuilding team, this probably isn't worth it, and as Eisenhardt recognized, you'd be selling out your future for the possibility of winning it all. Was it worth it for the Giants, who picked up Morris for 2006 and beyond? Only time will tell, but for the Giants, they are banking on needing only a few more wins in order to make it into post-season. And with Bonds in the last year of his contract, they feel they need to win now. And now, regardless of whether they do win it all or not, it's going to be a long and painful rebuilding process in San Francisco.
One of the articles I recently read from the New Yorker DVD's is a profile of former Oakland A's president Roy Eisenhardt by Roger Angell. It was published in the August 15, 1983 issue of the magazine. Eisenhardt was clearly a man before his time:
The delivery systems of baseball are a great concern now---or should be. Television is more important than ever. . . but televised baseball is almost an auto-immune disease. We're consuming ourselves. We're attacking our own system. Baseball can't really be taken in on television, because of our ingrained habits of TV-watching. Anybody who knows the sport understands that the ninth inning is as valid as the first inning---that's why real fans always stay to the end of a game. But we don't watch TV that way. If the other team scores four runs in the first inning we go clicko, or else we flip the dial and watch Burt Reynolds. On TV, the primary emphasis becomes the score and the possibility of the other team's changing it, and so we miss the integrity of the nine innings and those multiples of three---three strikes and three outs.
Baseball is a terrific radio sport, by contrast, because radio feeds our imagination. . . I think baseball has survived all this time because of its place in our imagination---because we've chosen to make the players and the games something larger than they really are. But television has just the opposite effect.
More good stuff tomorrow.