Park Factors

Through Six Weeks

The middle of May is a good time to take a look at the park factors around the league.

Granted, its waaayyy too early to draw firm conclusions about these; most teams still haven't finished home-and-homes with their opponents to date, and the overall sample size is still small enough that chance has a lot to do with the results. Fact is, though, it's a fun thing to look at.

Here's what the BP park factors would look like for just the 2002 season, based on games through Sunday, May 12. In most places--like the book, the Web site--we use a three-year average, so I'm also listing the three-year average for the 1999-2001 period, for the 2000-2002 period (using values to date for 2002), and the difference between 2002 and the expected average coming in.


               2002  99-01  00-02   Diff

Anaheim         930   1029   1003   -99
Arizona        1073   1014   1047    59
Atlanta        1111    982   1038   129
Baltimore       909    963    943   -54
Boston         1001   1023   1008   -22
Chicago Cubs    958    984    951   -26
Chi. White Sox 1045   1026   1047    19
Cincinnati     1180   1018   1082   162
Cleveland      1026   1026   1025     0
Colorado       1017   1208   1139  -191
Detroit         994    990    991     4
Florida        1024    954    986    70
Houston        1130   1060   1083    70
Kansas City     992   1054   1044   -62
Los Angeles     982    938    942    44
Milwaukee       885   1001    943  -116
Minnesota      1000   1053   1035   -53
Montreal        976   1025   1006   -49
NY Mets        1002    945    958    57
NY Yankees     1028    982   1020    46
Oakland        1148    976   1029   172
Philadelphia    912   1002    966   -90
Pittsburgh     1015    997   1006    18
St Louis        975   1000    995   -25
San Diego       911    934    917   -23
San Francisco   899    920    913   -21
Seattle         883    933    916   -50
Tampa Bay       979   1003    994   -24
Texas          1064   1033   1040    31
Toronto        1012   1038   1034   -26

The average team is 61 points off their expected park factor; by the end of the season that should be down to about 30, giving you an idea of how far out of whack some of these numbers are right now.

The ones farthest away from what we expected are:

Colorado, 191 points below expected. You all know this story: Rockies management has been keeping their baseballs in a 90-degree, 40%-humidity chamber. I think the hype on this is a little overrated; if those numbers are correct, that works out to a dewpoint of 65 degrees or so, which is typical for an un-air conditioned summer day in Baltimore. In other words, it isn't that extreme of an environment.

Furthermore, a humid ball still would face some problems of air density. A curve ball still shouldn't curve as much, for example, no matter how wet the ball is. There could be a secondary affect, though, of softening the cover enough for the pitchers to get a really good grip on the ball and to get the seams to stick up higher. Whatever... run scoring in Colorado has essentially been normal this year, and not steroidal.

Oakland, 172 points above expected. This one is a shocker, since Oakland is traditionally a pitchers' park, and all of the other West Coast parks are hovering around their traditional ratings. The A's have been this year's Rockies so far, scoring 5.8 runs at home and only 3.3 on the road--the biggest differential of any team in the majors. Their schedule has actually been fairly balanced, featuring home-and-homes with Anaheim, Seattle, Texas, Chicago, and New York, plus homestands with Boston (good pitching) and Toronto (bad). Statistical fluke.

Cincinnati, 162 points above. In 16 road games, the Reds have scored only 53 runs and allowed 46, an anemic 6.2 runs a game, the lowest figure in the majors. While their home numbers are a little high--at 10.0 runs per game, they rank third in the NL--it's the road numbers that do it.

Those 16 road games: four in Wrigley, which is posting its third consecutive season as a pitcher's park, and three each in Dodger Stadium (traditional pitchers' park with good pitchers this year), San Francisco (pitchers' park), Pittsburgh (neutral), and Philadelphia (neutral to hitters). Once their road schedule starts to even out, with the Arizonas and Houstons, their park factor will move back towards normal. It is conceivable that construction of the adjacent Great American Ballpark has changed the characteristics of Cinergy Field.

Atlanta, 129 points above. The Braves have scored just 3.1 runs per game on the road, worst in the majors, and their 6.4 total road runs per game is behind everybody except Cincinnati. They have been well-balanced, outscoring opponents 96-95 in 22 home games, being outscored 49-53 on the road. Part of the story is an anomalous 942 park factor in 1999, the lowest in the history of Atlanta baseball, holding down the "expected" score.

Milwaukee, 116 points below. Now this one might be more than just a fluke of the stats, although the odds are still that that's all it is. We don't have a track record to look at here to decide what is "normal" for this stadium. It may be a domed stadium--OK, retractably roofed--but it has such an open design that even when the roof is closed you can get a lot of cold air inside it. Neither team has scored more than eight runs in a game at Miller Park this season, while six of the Brewers' 21 road games have featured a nine-run effort or more, and those will even out during the season. Probably.

(Update, May 16. The Brewers and Reds just finished a four-game set in Miller Park, combining for 26 runs in four games. That will keep Milwaukee on the pitching side and Cincinnati on the hitting side.)

Clay Davenport is an author of Baseball Prospectus. You can contact him by clicking here.