While the majority of attention that St. Louis Cardinals fans have paid to the latest round of Hall of Fame voting has been devoted to Jim Edmonds, another member of the 100+ win squads of 2004 and 2005 is languishing on the ballot and will need a minor miracle to make the Hall.
Although his tenure with the Cardinals was brief, and St. Louis ranks a distant third in any honest assessment of his career, Larry Walker arguably has a better case for Cooperstown than Edmonds. Walker has a modest Wins Above Replacement edge per Fangraphs and a double-digit edge per Baseball Reference over Edmonds. Unlike Barry Bonds or Roger Clemens, fellow also-rans with superior statistical resumes, Larry Walker doesn't face any widespread suspicions of performance enhancing drug use.
And yet, a man who ranks 66th all-time in position player fWAR, ahead of such notables as Carlton Fisk, Ozzie Smith, and Willie McCovey, barely cleared 20% in his first three years on the ballot and dipped to barely over 10% over his last two years. And it's not as though Walker is merely a sabermetric darling of Blylevian proportions: his nearly 400 homers, three batting titles, and seven Gold Gloves are a case in and of themselves. It appears largely due to Coors Field.
By reputation, the home of the Colorado Rockies is the major-league equivalent of playing on the Moon. It is an environment which, particularly in Walker's prime, lent itself to inflated power numbers. For the definitive example of not letting a lot of home runs at Coors Field be the entire argument for a player's worth, look no further than Walker's former teammate, Dante Bichette, who in 1999 hit 34 home runs (granted, the league leader that year had 65, but this was still an impressive if not gargantuan total) and was worth -2.1 fWAR. Only 1937 Leo Durocher and 1999 Willie McGee were worse in a single season in the history of the St. Louis Cardinals.
But Larry Walker wasn't just taking advantage of the altitude of the Rocky Mountains. He was impressive defensively in a large Coors Field outfield and statistics such as WAR, which adjust not only for the offensive environments of the era but also of the ballparks, shine a favorable light upon his career.
Amidst rumors that the Cardinals are in talks with the Rockies about acquiring one of their incumbent outfielders, it is beneficial to look at park-adjusted numbers. Although the home run totals are not quite as absurd as they were in the 1990s, they are still high enough that it is worth monitoring, but not to a point where players ought to be completely dismissed based on their home field.
The biggest name among Rockies outfielders is Carlos Gonzalez. And in his career, Gonzalez has a home wRC+ of 137 and a road wRC+ of 101. In 2015 terms, this is the difference between J.D. Martinez and Charlie Blackmon (more on him in a bit): a very good hitter and a very average one. But these should be viewed no differently than the home/road splits of a non-Rockie, as wRC+ is a measure of a player's production adjusted for location. In 2015, for instance, the Rockies had a league-high .841 OPS at home, but by wRC+, they were actually a below-average offense, with a 94 wRC+, tied for 24th in MLB with the Cincinnati Reds, whose home OPS was .728.
As for Charlie Blackmon, his 2015 OPS is .797, which adjusted for Coors Field puts him, as I mentioned before, at a 101 wRC+, which is ever-so-slightly above average. It would be foolish to look at his OPS, note that it was the same in 2015 as Jason Heyward's, and assume that he was as good of a hitter as Jason Heyward, who of course had a .797 OPS at the somewhat pitcher-friendly Busch Stadium. But at the same time, it would be foolish to whitewash his numbers as a byproduct only of freakish environment when numbers exist and are freely available which contextualize his production and suggest that Blackmon was an average hitter, no more and no less.
With regards to Corey Dickerson, his career .879 OPS, all of which has occurred in the offensively-suppressed baseball timeframe of 2013 to 2015, initially seems too good to be true for an allegedly available club-controlled twenty-six year old. Among players since 2013 with 900 or more plate appearances, Dickerson ranks 15th in OPS, sandwiched between Nelson Cruz and Josh Donaldson. Corey Dickerson has not been the 15th best hitter in baseball since 2013, but it's not because Coors Field made some random guy look great: it's because Coors Field made a good hitter look like a great hitter. His hitting company on the wRC+ leaderboard isn't quite as illustrious (his 124 wRC+ puts him in a tie with Starling Marte and two points behind Michael Cuddyer) but it nevertheless does reflect positively on Dickerson as a hitter.
I say this to point out that the temptation to ignore players for playing in Denver still exists to this day, as evidenced by Larry Walker's lack of serious Hall candidacy. How much the same bias which persists with MLB media exists within MLB front offices is impossible to know, but in an era where any new statistic worth its salt adjusts for park factors, fans need not be inherently concerned that a good Coors Field player will not be productive in other cities.