July 18, 2000
NL West Notebook
Baseball at Altitude
We're in Year Eight of major-league baseball in Denver, which means we're approaching a point when we should have enough data to start determining what type of baseball, and what type of player, is best-suited to winning at altitude. We've seen a few different ideas implemented so far, as the Rockies have moved through flyball hitters with so-so OBPs to the current media-friendly speed 'n' defense model.
This Notebook won't be proffering a solution: that's a long-term project that we at Baseball Prospectus hope to attack in the next year. But what I want to do here is point out just how dramatic an effect playing in the high-altitude environment of Denver has on performance.
A personal pet peeve is that even after nearly a decade, this effect is underestimated by many fans and much of the baseball media. References to Enron Field as being almost as good a hitters' park as Coors Field dramatically understate the effect Denver has on run-scoring and the elements thereof. Any discussion of the Rockies--or assembly of the Rockies--has to start from this point.
As an example, let's take a look at the NL West offenses, first by actual runs, then by Clay Davenport's Equivalent Runs, which adjusts for ballpark:
Team Runs Rank NL Team EqR Rank NL
The offense that appears to be the third-best in the league is actually the league's worst. That kind of effect can't be overstated. It just can't.
It works the other way, too. Take a look at the division's rotations, first as measured by ERA, then by Michael Wolverton's Support-Neutral Winning Percentage. SNPct. adjusts for both park and the work of relievers following a starting pitcher:
Team StERA Rank NL Team SNPct. Rank NL
The Rockies' rotation looks like the worst in the league until you account for the environment. After adjustments, it's just a bit below average and comparable to the Dodgers' starters.
We can use another Michael Wolverton metric, Adjusted Runs Prevented, to see just how the park distorts the performance of the Rockies' bullpen:
Team RlERA Rank NL Team ARP Rank NL
The Rockies have the best bullpen in the National League, despite an ERA right around the league average for relievers.
According to Clay Davenport's calculations, games in Denver in 2000 have featured 38% more run scoring than games at an average park. The next-best environment for increasing offense? The Ballpark in Arlington, at about 16%. Not only is Denver the highest-offense environment in baseball, but that environment has more than twice the impact of the next-most extreme one.
Denver is completely off any known scale of park effects. Any evaluation of the Rockies, individually or as a team, has to take that into consideration. Not just pay lip service to the idea, but completely accept that everything has to go through the filter.
Joe Sheehan can be reached at email@example.com.