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.)