Way back in the late 20th century, Conventional Wisdom held that when Colorado Rockies hitters became ex-Colorado Rockies hitters, they would suddenly become poor hitters. Or at the very least, they would post numbers comparable to their road stats while playing for the Rockies. And their road stats while playing for the Rockies generally weren't particularly impressive.

But has it actually happened that way? The answer to this question will be particularly important to whichever team ends up with Larry Walker (assuming of course that the Rockies are able to trade Walker).

	Larry Walker Right fielder Colorado Rockies Profile
	2002 SEASON STATISTICS GM AB HR RBI OBP AVG 136 477 26 104 .421 .338

To check, I located 10 players who totaled at least 600 at-bats for the Rockies over the course of two seasons, then racked up more than 300 at-bats for another team in the following season. The two seasons with the Rockies suggest an established level of performance, while the next season -- the first season with another club -- will, with luck, give us an idea of what happens to ex-Rockies.

(I should note that this group of 10 players include three -- Eric Young, Ellis Burks, and Neifi Perez -- who were traded by the Rockies during the season. All three were actually traded fairly late in the season, so their "before" performance includes the previous full season and the partial season in which they were traded, and the "after" includes the rest of the season in which they were traded and the entire next season.)

So does the loss of Coors Field as one's home ballpark lead to significant drop-offs in the following season?

Sometimes it does, and sometimes it doesn't, and there is certainly not any obvious rule when it comes to ex-Rockies hitters. They do not, for example, revert to their road performances after losing the advantage of playing half their games in the rarefied Rocky Mountains air. The Conventional Wisdom has not, to this point at least, proved particularly wise.

Granted, five of the 10 players have seen their performance suffer in their first season (or season-plus) after leaving the Rockies, and three of them disastrously so. On the other hand, five of the 10 have seen their performances hold steady or actually improve after leaving the Rockies.

Here are the aggregate numbers:

 
        Games    AB    OBP  Slug  OPS 
Before   2732  10210  .352  .466  819 
After    1424   5225  .339  .411  750 

That's a big drop, of course, but it's due almost entirely to the three disasters: Vinny Castilla, Neifi Perez, and Jeff Cirillo. In all three cases, their immediate post-Rockies OPS's dropped by at least 25 percent.

Two other players dropped off, but in far less spectacular fashion; Eric Young's OPS dropped by seven percent, Dante Bichette's by six percent.

And so that leaves five players who did not suffer large drops in their production, at least as measured by OPS (on-base percentage plus slugging percentage). Here are all 10 players, their before-and-after OPS's, and the percentage change:

 
          Before  After  Change 
Castilla    881    562    -36% 
Cirillo     854    629    -26% 
Perez       752    567    -25% 
Young       795    741    - 7% 
Bichette    880    826    - 6% 
McCracken   752    745    - 1% 
Galarraga   966    991    + 3% 
Burks       902    933    + 3% 
Girardi     674    720    + 7% 
Weiss       639    729    +14% 

It's certainly worth noting that neither Joe Girardi nor Walt Weiss played every day in their first post-Rockies season, which makes their stats in those seasons less significant than they might otherwise be. Take that into consideration, and we might look at this list and conclude that three ex-Rockies dropped off the face of the (statistical) planet, while the other seven pretty much held steady.

So after all of these (statistical) maneuverings, what might we conclude about the prospective future of Larry Walker? First, we might conclude that he's more likely to go into the tank than significantly increase his production. But of course, he doesn't need to increase his production at all to remain a hugely productive hitter. He only needs to maintain his production. And we might also conclude that despite playing half his games in Phoenix (or wherever) rather than Colorado, Larry Walker will remain a productive player.

That is, when he's healthy enough to play. It says here that instead of worrying about Walker's adjustment to sea level (or thereabouts), his next employers should worry about his ability to stay in the lineup. Walker's played as many as 150 games in a season only once in his career, and that was back in 1997.

And you know, he ain't getting any younger.

Senior writer Rob Neyer, whose Big Book of Baseball Lineups will be published next spring by Fireside, will be appearing here regularly and irregularly during the offseason. His e-mail address is rob.neyer@dig.com.