The Last Park Factor Show

Dave Paisley

Last week, I showed you some of the curious home/road splits for the American league, and introduced some crazy concepts explaining how teams are able to take good advantage of their home ballparks. Now it's the National League's turn. In many ways, the NL is richer for park effect data, because it includes both Coors, an offensive powerhouse, and Dodger Stadium, an offensive sinkhole.

I explained how various park factors are calculated last week, so you may want to refresh your memory if it's not quite clear to you now. Here are the raw OPS numbers, ordered by the traditional Runs Scored Park Factor. Visitors' OPS is the OPS of teams playing at the park of the team in that row, and the Opponents' Home OPS is the OPS of the home team when the team in that row is on the road. Got that?
 

Team	Home OPS	Road OPS	Visitors'  OPS	Opponents' Home OPS	OPS  Park Factor	Runs Scored Park Factor
Rockies	.901	.712	.839	.763	118	159
Phillies	.765	.681	.773	.752	107	114
Cardinals	.807	.755	.717	.775	100	104
D-Backs	.731	.683	.745	.768	102	103
Brewers	.728	.724	.787	.789	100	103
Cubs	.804	.739	.749	.772	103	102
Pirates	.724	.649	.696	.754	101	102
Reds	.745	.733	.729	.765	98	102
Braves	.812	.778	.673	.639	105	100
Astros	.819	.765	.686	.731	101	97
Mets	.722	.726	.696	.756	96	94
Marlins	.689	.690	.781	.870	94	91
SF	.797	.753	.718	.764	100	90
LA	.694	.700	.652	.748	93	82
Expos	.683	.724	.692	.792	91	81
SD	.706	.769	.616	.782	85	73
Average	.758	.724	.722	.764

After a relatively quiet year at Coors (only a 133 Runs Scored PF last year), Coors jumped way up again. It has been in the 170s before now, though. In many ways, it's a good indicator of how volatile park factors can be from year to year, reinforcing my belief that single-year park factors are next to meaningless. Most parks typically vary by a range of 10 or so. In a future article, I'll be looking at the relative stability of park factors over time, for both Runs Scored and OPS. I suspect the latter will show less random variation, but we'll just have to find out.

The Runs Scored factor correlates reasonably well with the OPS factor. The only significant deviation is Candlest..., sorry, 3Com, where the Giants and their opponents managed to combine for identical OPS numbers overall, but managed to score 10% fewer runs at 3Com than on the road. To a lesser extent, Turner Field generated more OPS, but the Braves and their opponents couldn't make any extra runs out of it. As expected, LA is near the bottom of the table, but Qualcomm wins the best pitcher's park award hands down. Maybe Kevin Brown really likes that border cooking?

The next table looks at each team's home/road OPS ratios, as well as their opponents in those same games.
 

Team	Home OPS /Road OPS	Opponents' OPS  in this park /in their park
Rockies	1.265	1.100
Phillies	1.123	1.028
Pirates	1.116	.923
Cubs	1.088	.970
Astros	1.071	.938
D-backs	1.070	.970
Cardinals	1.069	.925
SF	1.058	.940
Braves	1.044	1.053
Reds	1.016	.953
Brewers	1.006	.997
Marlins	.999	.898
Mets	.994	.921
LA	.991	.872
Expos	.943	.874
SD	.918	.788
Average	1.048	.947

Not surprisingly, Colorado leads the pack in home/road advantage. However, their opponents also do better there than in any other park, not surprisingly. But to the Rockies' credit, they take better advantage, giving them a net gain. Of course, this means they could just be a really bad road team.

At the other end of the scale, no team does worse at home than the Padres. But look at how badly their opponents get killed at Qualcomm. So, despite the relatively low offense in Qualcomm, the Padres got a huge advantage there this year. Another interesting park is in LA, where the Dodgers actually get about the same offense as on the road, but their opponents don't. So does the mythical offense-reducing power of Dodger Stadium only apply to the opposition?

Of course, there is a natural bias in favor of the home team - the average team gaining almost 5% in OPS at home, while the average road team loses 5%. The following table takes out those inherent biases, and the final column is a measure of how much extra advantage each team took in its own park (or failed to produce on the road...)
 

Team	Adjusted  Team  Home OPS /Road OPS	Adjusted  Opponents' OPS  in this park /in their park	Team /Opponents' Adjusted OPS
Pirates	1.064	.975	1.092
SD	.876	.832	1.053
Cardinals	1.020	.977	1.044
Rockies	1.207	1.161	1.039
Astros	1.021	.991	1.030
LA	.946	.921	1.027
SF	1.010	.993	1.017
Cubs	1.038	1.025	1.013
Marlins	.953	.948	1.005
D-Backs	1.021	1.025	.997
Phillies	1.072	1.086	.987
Mets	.949	.972	.976
Expos	.900	.923	.975
Reds	.970	1.006	.963
Brewers	.959	1.053	.911
Braves	.996	1.112	.895
Average	1.000	1.000	1.001

It's something of a surprise to see the Pirates at the top of the heap, but right behind them is the aforementioned Padres. Colorado manages to take a small net advantage from Coors, as does LA from Dodger Stadium.  Strangely enough, right at the bottom are the Braves, who actually give up a fairly big advantage at home. Of course, they overwhelmed their opponents anywhere they played, so it doesn't really matter much this year, but if that trend continues, it may point to problems at home. Maybe it's the nauseating sight of Ted 'n Jane tomahawk chopping their way through every game. Milwaukee is the only other team that has a relatively  hard time at home.

So that's it for now on park factors.

 

about the author

Dave Paisley has turned his entire life up to this point into a scatter graph. Ask him exactly how the "ex-girlfriends" data point relates to the "Dean Palmer" point at drdjp@strikethree.com.