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Erboes wrote:Help me out here, fellas. I was reading something on the Coors field effect on hitting and although it makes perfect sense to me on paper, it makes no sense to me in reality. To sum up the calculations, there is a 20% bump a Rockie hitter gets playing at Coors, but on the road there's a -19% "hangover effect" for those same hitters. So, in short, there's only a 1% bump a player will get by playing for the Rockies. Am I correct in my calculations when I say a .280, 20 homer, and 90 RBI player in a normal hitting park will become a a whopping .283, 20, and 91 after being traded to the Rockies? I don't know about you fellas, but this seems like a bunch of matchematical mumbo-jumbo to me. What say you baseball gurus out there?
Erboes wrote:Here's the full piece I was reading:
Here's the full-blown calculation:
In order to determine how much Rockies hitters' numbers are boosted by Coors, we need to know three things:
A) The conventional Coors park factor.
B) The extent to which the hangover effect hurts our hitters' overall numbers.
C) The extent to which the hangover effect affects the conventional Coors park factor.
The overall hangover-adjusted Coors park factor, then, would be A-B-C.
We know that A is approximately +20%, as Lou mentioned.
What about B? Well, according to the link that Lou gave, the hangover effect reduces hitters' road OBP and SLG from .339/.411 to .302/.363. Using OBP*SLG, we then find that that is equal to a 27% reduction in runs created in road games, which translates to a 13% reduction overall (I rounded down because most of our hitters' PA's come at home).
Now, onto the tricky one. How does the hangover effect affect the conventional park factor? Let's put it in equation form:
RSH: Runs scored at home
RAH: Runs allowed at home
RSR: Runs scored on the road
RAR: Runs allowed on the road
The conventional park factor is calculated as ((RSH+RAH)/(RSR+RAR)+1)/2. Set all four variables equal to one another to calculate the park factor of a neutral park; obviously, this is equal to 1.
Now, to account for the hangover effect. Let's first set all four variables equal to 4.61, the average number of runs scored per game in the 2003 NL. Now, the hangover effect reduces RSR by 27%, so we replace RSR with 4.61/1.27, or 3.63. Now we calculate the park factor, and come up with 1.06. That means that the hangover effect, by itself, inflates the conventional park factor by 6%. This is our value for C (in my first equation).
So we have our answer. The park factor equals A-B-C, where A=+20%, B=-13%, and C=-6%. Therefore, Coors inflates Rockies hitters' numbers by 1 percent.
Obviously, that's not an exact calculation; we don't know enough about the hangover effect (or about the Coors inflation effect) to come up with a precise answer. But it's pretty close, and it certainly goes to show that any system that does not account for the hangover effect is completely worthless when it comes to evaluating Rockies hitters.
End quote
I think it has to be a bunch of garbage too, but maybe some of the statistical guys here can shed some light on this.
Ramble2 wrote:Is the claim that Rockies hitters actually hit worse in other ballparks than every other hitter? So much worse that over a season we shouldn't expect any bump in stats from hitting at Coors?
Ramble2 wrote:Is the claim that Rockies hitters actually hit worse in other ballparks than every other hitter? So much worse that over a season we shouldn't expect any bump in stats from hitting at Coors?
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