Archive for May, 2008
Zubin Jelveh at Portfolio offers more evidence that weather is not responsible for the power declines in baseball. He looks at slugging percentages in domed stadiums, where temperature ought to be less of a factor.
Recently, there has been some discussion about the disparity in run-scoring between the AL and the NL. For example, here are two articles on the subject by William Burke and Joe Sheehan, and David Pinto. Because of the designated hitter, AL teams tend to score more runs and hit more home runs than NL teams. This year, this has not been the case. In my investigation of the impact of temperature on home-run hitting I looked at the differences in early-season temperatures between the leagues.
Here are April home run and temperature data from 2000-2008. The temperature data exclude indoor games.
AL NL Year HR/G Outdoor Temp HR/G Outdoor Temp 2000 2.60 62.03 2.57 63.90 2001 2.32 60.19 2.35 65.48 2002 2.12 60.31 1.74 64.64 2003 2.13 58.35 2.08 62.79 2004 2.20 60.82 2.13 66.40 2005 1.96 61.82 1.85 64.68 2006 2.42 62.21 2.21 66.13 2007 2.04 57.85 1.69 62.49 2008 1.73 61.53 1.83 65.00 00-07 2.22 60.45 2.08 64.56 08 Diff -0.49 1.09 -0.25 0.43
The data reveal some useful information. AL teams typically play in colder whether than NL teams. But, even though April 2008 was colder in the AL than in the NL, AL baseball was over a full degree warmer than it had been in the previous eight seasons, while NL baseball was under half-a-degree warmer. Home runs in the AL were down by half-a-HR per game (22%) and NL homers were down by a quarter-a-HR per game (12%) in 2008. This is not looking good for the temperature hypothesis.
Let’s take a closer look at the league differences in home runs and temperature by year.
HR Gap Temp Gap AL-NL NL-AL Year HR/G Temp Temp Impact 2000 0.03 1.87 -0.03 2001 -0.04 5.29 -0.08 2002 0.38 4.33 -0.06 2003 0.05 4.43 -0.07 2004 0.06 5.57 -0.08 2005 0.11 2.86 -0.04 2006 0.21 3.92 -0.06 2007 0.36 4.65 -0.07 2008 -0.10 3.46 -0.05 00-07 0.14 4.11 -0.06 08 Diff -0.24 -0.65 0.01
In Aprils from 2000–2007 AL teams averaged 0.14 more home runs per game than NL teams did, while NL games were played in parks that were 4.11 degrees warmer than AL parks. In 2008 the temperature gap between leagues actually shrank, as AL teams played in warmer conditions than NL teams relative to the past; therefore, the homer gap should have increased rather than decreased and reversed.
The final column of the table above measures the impact of the temperature gap on HR/G differences between leagues, using the 0.015 impact that each degree contribute to home runs that I discussed in my previous post. This captures the impact that temperatures have on narrowing the home-run gap between the leagues. From 2000–2007, higher temperatures in the NL have kept the homer gap 0.05 home runs per game less that it would be under the same temperature conditions. This means that if the AL and NL played in the exact same temperature environments, the homer gap would be 0.05 home runs per game higher than it has been. Based on temperature, the AL homer gap over the NL should have increased by 0.01 home runs per game in 2008. Therefore, it seems that temperature differences do not explain the change in home-run rates between leagues.
Again, I reiterate what I said about the fluctuation of home runs in my previous post. It’s very difficult to pin the decline in home runs this season on something other than random variation. As Bob Nightengale points out in the USA Today, home run rates are not all that different this season than they were a few years ago.
Since my original post on the relationship between temperature and home runs I had wanted to follow up with game-specific data. This was slowed by my inability to get good 2008 data and going out of town. After banging my head against the wall trying to use Perl to parse MLB Gameday data I did what I should have done in the first place: I asked my buddy Doug Drinen for help. Though he doesn’t like intentional walks, he is a Perl grand master, and he parsed the 2008 data in a matter of minutes. I want to offer him a huge thanks for doing this.
So, I left off last time looking at average US temperatures in April and home-run rates. What I really needed was game temperatures. So, with the help of Retrosheet, Gameday, and Doug, I was able to look at home runs and temperature by game. The data below lists the mean home runs per game and temperatures in April by year. The temperature data excludes games played indoors.
MLB Year HR/G Outdoor Temp 2000 2.59 63.12 2001 2.34 63.19 2002 1.92 62.73 2003 2.10 60.87 2004 2.16 63.97 2005 1.91 63.46 2006 2.30 64.45 2007 1.85 60.59 2008 1.78 62.76
While temperatures were down in 2008, they were higher than they were in 2007. 2006, which had a high home-run rate, was hotter than 2007 and 2008. Some commentators have compared this season’s decline in homers to 2006 and have concluded that the decline in steroid use is a big contributor. Here is a sample from Thomas Boswell.
This spring, for the second straight year, home run totals, like the game’s conspicuous muscles, have shrunk dramatically. Last season’s 8 percent drop in home runs was welcomed, but with caution. Would the tater barrage simply resume? But now, in the wake of the Mitchell report, home runs have fallen this spring by another 10.4 percent.
Suddenly, a sport that produced 5,386 home runs in 2006 is on pace for 4,442 this year — a 17.5 percent drop, or a loss of almost 1,000 home runs in just two seasons.
2006 is an odd year for comparison, because serious testing really began in 2005, with suspensions for one failed test. (Check out MLB’s drug policy timeline.) The lost 1,000 homers is a good headline, but the number of homers in 2006 actually hurts the case that testing has lowered steroid use because it occurs after testing began.
But even though 2006 was hot, and 2006 and 2007 were relatively cool, the change in temperature isn’t enough to explain the difference. Comparing the averages from 2000-2004 (pre-testing) to 2005-2008 (testing), the decline in temperature only explains a small portion of the change in home runs.
Years HR/G Outdoor Temp 00-04 2.22 62.77 05-08 1.81 61.67 Diff. 0.41 1.10 Impact of temp on ΔHR/G: -0.0165 %Δ expl by temp: 4.06%
I used a negative binomial regression to estimate the number of home runs in a game as a function of temperature, league, and park (using park dummies) from 2000–2007 for outdoor games. (The first person to say “why don’t you control for X, Y, or Z” gets a maple bat shoved up his/her rear end. It’s a simple model, but it gets the job done. If you don’t like it, estimate your own damn regression.) The model estimates that each one-degree change in temperature adds approximately 0.015 home runs per game. The magnitude of the effect is meaningful: the difference between average April and July temperatures adds about one home run per four games played. However, in explaining a shift in temperature from the pre-testing and testing eras (0.41 HR/G), it only explains four percent of the decline in homers. Even looking at the extreme April temperature difference between 2006 and 2007, the temperature change only explains about 6% of the decline.
Does this mean that steroid testing is the cause of the fall in home runs? No. These numbers bounce around quite a bit, and it’s just too soon to say whether or not we are seeing a real change or whether this is just a product of random fluctuation or other factors. Just look at 2002 and 2006. What we can say is that while low temperatures are contributing to the drop in homers, they don’t explain much of the change.
I’ve got more coming on this, but I’m short on time. I may not get to it until next week, but I have also looked into the impact of temperature on the difference in home runs between leagues.
I’m not sure why, but it seems that there has been a lot of talk regarding rule changes this year. In an interview with Chris Young yesterday, Rob Neyer stated he would like to do the following.
I would outlaw the intentional walk. I would shorten the season by two weeks, by shortening the schedule to 154 games and scheduling five or six doubleheaders per team. I would — and this is something Bill James has been recommending for years — standardize and supply the bats. I would shorten the time between half-innings by 30 seconds. I would order the umpires to enforce the rules prohibiting fielders from blocking bases (including home plate) [Ed. note: This was days before Albert Pujols cleaned out Josh Bard]. I would do whatever I could to lower the number of pitching changes. Oh, and I would set a maximum decibel level for ballpark sound systems that would result in a great deal less noise than we hear now. (Yes, I know… Hey, you stupid kids! Get out of my yard!)
There is nothing unique or unreasonably about the items on the list, I just want to use one of his suggestions as a foil. As the title to this post indicates, I love the intentional walk. One of the most beautiful aspects of baseball is that the defense is the first mover before each play. In most other sports, the team/person attempting to score is the first mover. In football, the offense calls the play. In basketball, hockey, and soccer (which are all really variants of the same game) the player possessing the ball/puck makes the decision of how to move the scoring item. In tennis, the server decides how hard and where to hit the ball. In baseball, the hitter must respond to what the pitching team gives him.
The intentional walk is an interesting strategy that allows the opposition to obtain an outcome that the defense typically tries to prevent. When the free pass happens, it is interesting from strategic and competitive perspective. Is walking the opposing hitter a good idea? In most situations it’s a bad idea. But if it turns on a force-out, avoids a good hitter, or changes the platoon advantage it can be a smart move. Whether or not the decision is a good one is fun to discuss.
The effect on the egos of competitive men should not be overlooked. “I’d rather pitch to you than the guy in front of you” thinks the pitcher. “You’re walking him to pitch to me?” thinks the batter. Echoing The Godfather, this may seem like business, but when you get down to it this is personal.
Yeah, the intentional walk often does take the bat out of a good hitter, whom I would like to see hit. But to me, that is part of the game. Does it slow the game down? A little, but so does the third base coach calling time to talk to the batter about the signs, or the pitching coach strolling out to the mound to tell his pitcher to throw strikes. Until moments like these are gone, we shouldn’t include intentional walks in the speed-up-the-game discussion.
In summary, I ♥ the IBB.
Last week, I got a call from the AJC’s Tim Tucker about a story he was doing on the impact of the economy and gas prices on sports attendance. As I was on the road and away from my desk, I pondered a few possibilities but could not give a definitive answer.
J.C. Bradbury, an associate professor of sports economics at Kennesaw State University, said he recently read a couple of articles suggesting that sports is recession-resistant. He’s skeptical of that view. But he noted that consumer behavior can be tricky to forecast, even at current gas prices.
“Certainly, you would see that some of the people who [typically] come to Braves games from afar might not come,” Bradbury said. “But gas prices might make other people say, ‘Instead of going to the beach or to Disney World, let’s go to a Braves game.’ “
Tim’s question caused me to think about the topic a little more. I was particularly interested in the impact if fuel costs given all of the media coverage of gas prices over Memorial Day weekend. According to the Federal Highway Administration, driving is down 4.3 percent from last year. Does this mean fewer people are driving to the ballpark? As I sat in the Turner Field stands yesterday, I thought it might be useful to look at how team’s Memorial Day game attendance has changed over the past few years.
Over the past five years, gas prices have risen steadily according to the various news stories that I found on the web. (I couldn’t find an official list over time, so the numbers below are rough dollar-per-gallon estimates from news stories about Memorial Day travel costs.)
2008 $3.98 2007 $3.23 2006 $2.93 2005 $2.11 2004 $2.02
Basically, gas prices have doubled since Memorial Day 2004. Now, we know that MLB attendance has been increasing in general over the past few years, despite the rise in gas prices. Of course, this is because many other factors influence fan decisions to attend games. Obviously, baseball attendance isn’t highly correlated with gas prices. However, on the margin, individuals might be less willing to spend a few extra dollars to travel to see a baseball game. Or, if gas prices reduce long trips, locals may be more willing to stay in town and go to a baseball game instead of traveling to more distant destinations.
Here is a list of average Memorial Day game attendance from the past five seasons.
Year Mean Games 2004 29,736 12 2005 33,946 10 2006 31,534 14 2007 29,761 12 2008 34,012 11
Mean attendance at Memorial Day games was actually the highest it has been in recent history in 2008. But, an obvious distorting factor is the impact of the markets which are hosting the games. So, here is the average attendance at Memorial Day games from teams that hosted Memorial Day games in 2008. This way, factors unique to these markets are taken into account.
Year Mean Games Home Teams 2004 33,950 4 ATL, CHN, PHI, SEA 2005 32,623 2 SEA, WAS 2006 35,893 7 ATL, CHN, CLE, LAA, NYN, PHI, TOR 2007 33,905 5 CHN, LAA, PHI, TBA, TOR 2008 33,921 10 ATL, CHN, CLE, LAA, NYN, PHI, SEA, TBA, TOR, WAS
In 2008, mean attendance was up over the previous year, but was less than in 2006. I excluded Baltimore, because it did not host a Memorial Day game during the previous four seasons. When Baltimore is included the 2008 mean rises to 34,012.
This analysis is complicated by the fact that we are looking at a small number of games. To see the impact of individual games, it’s easiest to view the data as a graph.
It looks like some teams did better and some teams did worse. Certainly, factors other than gas prices are important (i.e., starting pitchers, team quality, weather), but it is just too difficult to control for all the other factors given the limited number of observations. Still, I think it is interesting that 2008 attendance was similar to what it was in the previous year. Given that baseball’s attendance has been rising, maybe this is a sign that gas prices are keeping baseball from growing further. But ultimately, I think gas prices are not having much of an impact on baseball game attendance.
Sorry for the lack of posts. I had planned a working vacation last week, and I just didn’t have as much access to the Internet as I had anticipated. I don’t have time to do anything new today, because I’m taking my four-year-old daughter to the Braves game this afternoon. I will leave you with a story from my vacation.
My father-in-law and I took the four-year-old on her first pre-sunrise fishing trip. It was nothing extravagant, dock-fishing for bream with bobbers, crickets, and ultra-light rods. About 6am, my bobber went under. The pond holds fairly large bluegill and shellcrakcer, so I wasn’t surprised by the drag going out. When the fish broke the water, I thought the sparse daylight was playing tricks on me. But, on the second jump, it was clear that I was fighting an exceptionally big largemouth bass. I’m used to managing fish on light tackle, so I was able to tire her out and get her to the dock. As I reached down to grab her lip, I noticed a tail hanging out of her mouth. Had the large shellcracker not been there, I could have put my fist in her mouth with room to spare.
I’ve hooked large bass like this before, but I’ve never managed to land one. The problem with two-stage fishing—fish eats bait, then becomes bait—is that once the bass realizes what is going on, she releases the hooked fish. This case was different because the shellcracker was so large that its fin barbs acted like hooks. I saw no way to remove the shellcracker from the bass’s mouth. Because I had no desire to eat a six–seven pound bass—I would have eaten the shellcracker—I cut the line and put her back in the water in hopes that she would swallow her prey. I saw her jump half-a-dozen times trying to throw the fish. I assume she finally swallowed it. But anyway, it was a good fishing story to tell during the fish fry that night. It’s too bad I didn’t have a camera with me.
From the Gwinnett Daily Post.
DULUTH – Gwinnett tourism officials are reaching out to local cities for help in hospitality efforts.
Recently, members of the Gwinnett Convention and Visitors Bureau have worked to convince leaders to create a uniform hotel/motel tax rate across the county, where 2 percent of the 7 percent tax would go to the county bureau….
The county’s hotel/motel tax rate is 7 percent, but hotels in cities pay rates determined by each City Council. The bureau is proposing a 7 percent charge so 2 percent could be dedicated to the bureau….
“We’re willing to talk,” Buford City Commission Chairman Phillip Beard said, adding that he understood the bureau’s need for additional revenues with the construction of a minor league baseball stadium planned for Buford Drive south of the city. [Emphasis added.]
Another example of the Gwinnett Braves stadium paying for itself from day one.
For the second year in a row, home runs are down in baseball. It won’t be long until someone attributes this change to improved drug testing and the response to the the Mitchell Report. Here is a graph of March/April home runs (thanks to Baseball-Reference’s league splits).
Now, it is possible that testing might have had an effect, but it is not obvious in the data. MLB began random tests with sanctions for a first offense in 2005. Home runs were down in 2005, but they were not significantly different from prior years; and, in 2006 home runs returned to the 2004 level.
But still, there is no denying that home runs are down from recent historical highs. In fact, the home-run rate this year is the lowest it has been since 1993—the beginning of the modern home-run era. And this continues the decline from last season, when the home-run rate dropped below three percent for the first time since 1997. Are there any factors that could be causing this aside from a decline in drug use or random variation in the data?
It is easy to remember something very unique about last season’s first few weeks: it was unseasonably cool. Off the top of my head, I recall the Indians losing several games to snow and playing a home series with the Angels in Milwaukee. Chris Constancio looked at the impact of temperature on home runs and found strong positive relationship the two.
The average temperature for major league baseball games [in 2007], 58.2 degrees Farenheit, was over four degrees cooler than the average during the early part of the previous two seasons. This relationship seems relevant to understanding why home runs, and consequently run totals, are down this season….
Game-time temperature was a significant predictor (at the p [greater than] .001 level) of whether or not batted balls left the ballpark, but the day of the season was not statistically significant. A batted ball has a 4.0% chance of leaving the park during a game played in 70 degree conditions, but only a 3.5% chance of becoming a home run in a game played in 50 degree conditions. This relationship exists regardless of whether or not the game is being played during the first week of the season or in the middle of May.
In summary, it’s true that hitters gain an advantage in hitting home runs as the season progresses, but this advantage can be explained entirely by accounting for air temperature changes.
This year, I can only recall one snow-out (Braves–Rockies), and the early-season temperature hasn’t gotten as much press as it did last year. I decided to look at how the April temperature this season differs from previous seasons, and compare temperatures to home-run rates.
Over the past decade, early-season home runs and temperature have moved together. April 2008 was actually 0.3 degrees cooler than April 2007—sorry Al Gore*—and 5.12 degrees cooler than April 2006. This doesn’t mean drug testing has not affected hitting power, but we have have a decent alternative explanation for why home runs are down. So, make sure you point this out to the first person who claims drug testing is working.
*It’s a joke, no angry e-mails please.
UPDATE: Upon closer inspection, it appears that temperature changes do not appear to explain much of the decline in home runs. See the following links.
I believe that Paul DePodesta is the first MLB front-office executive to operate a blog: It Might Be Dangerous. I’m curious as to what he has to say. It looks to be mostly about the Padres, but he welcomes questions. I suggest asking him your advice about how to get a job in baseball. People often ask me for this advice, but I really do not have much to offer.