Houston’s new ballpark had barely opened last spring when sportscasters began calling it 10-Run Field. Enron Field indeed saw an average of 12.41 runs per game, 6.23 scored plus 6.17 allowed by the Astros.
Yet all the parks the Astros visited last season were a combined 10-run field, as the Astros averaged 10.83 runs scored plus allowed per game on the road. And Enron was only one of six National League parks to break the 10-run barrier:
Park R/G ------------------- Coors 14.37 Enron 12.41 Cinergy 10.43 Busch 10.25 Three Rivers 10.21 Olympic 10.07
An even less flattering nickname, at least to Houston fans weaned on the pitcher-friendly Astrodome, was Coors South. Enron and Coors Field were both hitters’ parks, and Coors is by no means smaller than Enron:
Park L LC C RC R ----------------------------------- Coors 347' 390' 415' 375' 350' Enron 315' 362' 435' 373' 326'
The big difference is altitude. Enron sits 22 feet above sea level, 5,258 feet lower than Coors. This is one reason Enron, while a premier hitters’ park, had nowhere near the effect on offense exerted by Coors.
A useful method to measure park effects is to compare the performance of a team’s hitters plus pitchers at home and on the road. It is best to exclude interleague games, since the presence of the designated hitter inflates offense in American League parks. A larger sample size is preferable to a single season.
Looking at the most fundamental unit of offense, runs, Enron paled in comparison to Coors. Here are the top 10 major-league parks from 1998 to 2000 in differential in runs per game:
Park Home Road Index ------------------------------ Coors 13.89 8.53 163 Enron 12.85 10.76 119 Arlington 11.90 10.65 112 Veterans 10.10 9.14 110 Metrodome 10.23 9.36 109 Jacobs 11.29 10.61 106 Kauffman 11.03 10.39 106 Cinergy 9.77 9.30 105 Busch 10.28 9.81 105 Fenway 9.90 9.52 104
Index is a ratio of performance at home to that on the road. This list shows that in 2000 Enron was among the best hitters’ parks in baseball. It likewise reveals that Coors was unquestionably the Babe Ruth of bandboxes. No other park came close.
Indeed, Coors is unmatched in this regard by any park since the 19th century. The only post-1900 parks to approach Coors are Philadelphia’s Baker Bowl, which the Phillies occupied until 1938, and Wrigley Field. But even Wrigley never distorted offense the way Coors does.
Not only did Enron fail to rival Coors in runs, it also trailed widely in home runs. Here are the top 10 major-league parks from 1998 to 2000 in differential in home runs per 100 at-bats:
Park Home Road Index ------------------------------- Coors 4.30 2.63 164 Enron 4.80 3.89 123 Busch 3.71 3.29 113 Arlington 3.65 3.26 112 Three Rivers 2.84 2.61 109 Kauffman 3.31 3.05 109 Comiskey 3.64 3.35 109 Cinergy 3.40 3.17 107 Jacobs 3.53 3.32 107 Edison 3.41 3.20 106
The home-run percentage was actually higher at Enron last year than at Coors the last three seasons. This creates the misimpression that Enron was a better park for home runs, but look at the numbers on the road. The differential at Coors was much greater than at Enron.
Coors also led all of baseball in differential in batting average from 1998 to 2000, although by a less extreme margin. While Enron finished in the top 10, it was not runner-up:
Park Home Road Index ---------------------------- Coors .320 .257 124 Fenway .274 .257 107 Jacobs .286 .270 106 Arlington .297 .283 105 Enron .286 .273 105 Kauffman .286 .273 104 BankOne .286 .255 104 Metrodome .280 .270 104 Veterans .266 .261 102 Wrigley .267 .265 101
It might appear that the characteristics of a team or its players determine park effects. It might seem intuitive that Busch Stadium was good for home runs or Fenway Park was conducive to batting average because Mark McGwire and Nomar Garciaparra, respectively, played half their games there.
Remember, though, that index examines not how many home runs were hit at Busch or what the batting average was at Fenway but how those statistics compare to the numbers on the road. If one team batted .300 at home and .300 on the road, and another team batted .240 at home and .240 on the road, their parks would have the same index despite a 60-point difference in batting average between them.
Wise teams build their rosters around their parks. Asymmetrical parks favor lefties or righties. Parks with turf are friendlier to speed than parks with grass. Parks with big outfields better suit flyball pitchers than parks with small outfields. But an individual player’s performance might comprise only five percent of the plate appearances in a park, not a significant influence on park effects.
Park effects as drastic as those at Coors certainly help determine how a team is perceived. At first glance it would appear that the Rockies have solid offense but awful pitching. Take a look at the statistics at home and on the road the last three seasons, however:
Batters R/G Avg OBP Slg HR% -------------------------------------- Home 7.06 .328 .389 .535 4.22 Road 4.03 .252 .312 .387 2.44
Pitchers R/G Avg OBP Slg HR% -------------------------------------- Home 6.84 .311 .378 .516 4.39 Road 4.51 .262 .340 .414 2.83
At 4.03 runs per game, the offense was absolutely anemic on the road. The pitching staff allowed 4.51 runs per game on the road, not bad these days. That they actually had poor offense and decent pitching contradicts the popular wisdom about the Rockies, though.
Lots of factors influence park effects: altitude, distance to and height of the fences, amount of foul territory, playing surface, visibility, air flow, climate. And park effects fluctuate annually based on weather and random chance, among other things. Thus, it is impossible to know whether Enron will continue to play like it did in its debut year.
The only offensive event in which Enron notably exceeded Coors was triples, which are such infrequent occurrences that Enron’s index could be very different next season based on a small change in the raw totals. For comparison, here are the indexes for Coors and Enron across the board:
Park R/G Avg OBP Slg OPS 2B 3B HR BB SO ------------------------------------------------------- Coors 163 124 118 131 125 114 148 164 101 84 Enron 119 105 104 113 109 118 202 123 102 99
While the statistics support the common knowledge that Enron was a great park for hitters, they debunk the myth that it deserved a reputation as Coors South. Enron’s closest cousin was not Coors but likely the Ballpark at Arlington, which exercised not dissimilar influences on runs, home runs, and batting average.
That means fans can look forward to the likelihood of plenty of fireworks at the Lone Star Series this June.