Now, the park is basically the same size, and it's at the same altitude. Why would the park factor vary so much from year to year? I know it's a calculated figure based on runs scored and allowed, but I would have said a genuine "park factor" should be fairly constant.
If the "true" figure for Chase can be anywhere between 97 and 111 in a given year, doesn't the random noise all but obscure the data? [A bit like clutch hitting] Or is it not just a park factor, but maybe "park plus defense"? [I tried reading the BR explanation, but lost consciousness around paragraph three ] Basically, what's the significance of these figures, and can they be used in any meaningful way to predict results going forward?
I also notice that last year was definitely more hitter-friendly than average. Looking at those stats, I'd expect a regression towards 2005's level, as the median seems to be at about 104. Maybe even lower, if our defense kicks in, as it should.
_________________
Jim McLennan
AZ SnakePit
Park Factors are affected by other parks as well. The PF isn't just RS and RA at home, it's also based off of RS and RA away. If you look at our NLW opponents, SD and LA saw jumps in their PF in 1999. COL saw a significant drop in 2003. These kind of things will affect us a lot with the unbalanced schedule. The humidor in COL would theoretically up our PF.
Now, the park is basically the same size, and it's at the same altitude. Why would the park factor vary so much from year to year?
I have never had much confidence in park factors due to the fluctuations that I have seen and my inability to find solid explanations/formulas to determine them.
If anyone has cool links on the subject, please post them.
Joined: 10 Aug 2006
Posts: 3242
Location: In front of my computer
Posted: Thu Dec 21, 2006 7:54 pm Post subject:
You are correct to be suspicious of single year park factors.
Here is a link for weighted park factors
Weighted Park factors
Park factors are never going to be perfect, for the reasons that Dylan pointed out. However, this is still better than a wild ass guess. Everybody knows certain parks tend to lean one way or the other. The attempts to quantify that, while imperfect, still get us closer to being able to contextualize production and performance better than not doing anything at all.
Park factors are never going to be perfect, for the reasons that Dylan pointed out. However, this is still better than a wild ass guess. Everybody knows certain parks tend to lean one way or the other. The attempts to quantify that, while imperfect, still get us closer to being able to contextualize production and performance better than not doing anything at all.
we can always use scouts and just <forget> the stats
A 9 year average from the chart above shows a run factor of 1.04 while this link has a three year average ( '03-'05 ) of 1.12 and snake pit's '03-'05 list averages 106.
A 9 year average from the chart above shows a run factor of 1.04 while this link has a three year average ( '03-'05 ) of 1.12 and snake pit's '03-'05 list averages 106.
I'm very confused regarding these fluctuations.
Any ideas???
Like most things, you can make them as complicated or simple as you want. The simplest form is this:
((Home RS + Home RA) / Home Games) / ((Road RS + Raod RA) / Road Games)
This gives you the run environment park factor for 1 year. A simple weighted avg would be (3*this year + 2*last year + year before that) / 6
Joined: 10 Aug 2006
Posts: 189
Location: Scottsdale, AZ
Posted: Fri Dec 22, 2006 1:27 pm Post subject:
Dylan wrote:
Park Factors are affected by other parks as well. The PF isn't just RS and RA at home, it's also based off of RS and RA away. If you look at our NLW opponents, SD and LA saw jumps in their PF in 1999. COL saw a significant drop in 2003. These kind of things will affect us a lot with the unbalanced schedule. The humidor in COL would theoretically up our PF.
And that's a large chunk of my problem. It's not really our "park factor" if it's affected by the behavior of other parks. The value for Chase would depend partly on the values for the other parks. Which would, in turn, depend partly on the value for Chase. My head hurts... I can't see any way of avoiding this, because you need to compare the runs scored at home with *something*.
But I think with a park-factor, you should be aiming to find the true value, which would be something constant - another season is just another point of data towards this end. Why weight the recent ones more heavily?
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Jim McLennan
AZ SnakePit
Joined: 10 Aug 2006
Posts: 3242
Location: In front of my computer
Posted: Fri Dec 22, 2006 2:01 pm Post subject:
well, there are alot of factors that might affect a park from year to year...(less so in chase field of course)
Weather and wind patterns
Changes in the hitters background in CF
Changes in the dimensions of the OF
Changes in the dimesnions of the foul territory
Other external factors, such as the Humidor in Colorado
For example, a couple of years ago they made changes to the hitters background in CF in Dodger Stadium, and also added seats that reduced the amount of foul territory. That obviously affected how Dodger Stadium played.
Back in the early 80's I believe, (not sure of the exact year) they added a structure on the roof behind home plate at Fenway, and that changed the wind patterns out to left field. In todays Fenway Park, maybe Bucky Dents homer does not go over the wall.
Wrigley often plays like two different parks, with the wind tending to blow IN during the months of April, May and September, but OUT during the months of June, July & August.
And as for Coors field, over the last couple of months of the season, it actually played like the coors field of old. This may or may not have been due to Changes in the use of the Humidor.
Ballpark factors are generally not "static".
That said.....there are identifiable trends. With the exception of 1999, Chase/Bob has ALWAYS played as a hitters park....and with the exception of a coulpe of outlier years, for the most part has been within an identifiable range.
Joined: 10 Aug 2006
Posts: 3242
Location: In front of my computer
Posted: Fri Dec 22, 2006 2:32 pm Post subject:
Here is my E mail to Dan, and his response:
Quote:
Dan, I was wondering if you could help me out with something.
In your 2003-2005 wieghted park factors, Arizona is listed with a 112 (runs).
This is a little confusing to me, as per baseball-reference park factors, the park factor was 111 in 03, 103 in 04, and 104 in 05.
Are you sure the 112 weighted park factor listed for arizona was correct?
Also, have you posted an updated version of this, 2004-2006, I couldn't find it.
Thanks for taking the time to answer, I know you are busy.
Regards
Shoe
Response:
Quote:
Shoe,
You're actually looking at two different things here. The park factors I posted that time were simply the "straight-up" park factors of home stuff divided by road stuff while the B-R park factors are park factors already divided by the effect of 81 road games so that the park factors can neatly multiply to OPS+ and ERA+ for individual players. Check out step 3 in the park factor glossary.
Do you need the factors for something in particular? I have the 04-06 multipliers on my MLE spreadsheet if you need them.
dan
Baseball Ref Glossary
The Bball Ref park factor was 107 hitters/106 pitchers for 2006
Just using straight Runs, I came up with 114 park factor
832 Runs scored in chase field, 10.27/g
729 Runs scored in road games. 9/g
Like most things, you can make them as complicated or simple as you want. The simplest form is this:
((Home RS + Home RA) / Home Games) / ((Road RS + Raod RA) / Road Games)
This gives you the run environment park factor for 1 year. A simple weighted avg would be (3*this year + 2*last year + year before that) / 6
Thanks for your input Dylan. Any theory behind why the 3,2,1 factors are important?
shoewizard wrote:
But that wouldn't explain how Dan came up with 112. He is using 8,5,3 by the way.
I assume that "8,5,3" means the weight placed upon each year's info?
Quote:
Shoe,
You're actually looking at two different things here. The park factors I posted that time were simply the "straight-up" park factors of home stuff divided by road stuff while the B-R park factors are park factors already divided by the effect of 81 road games so that the park factors can neatly multiply to OPS+ and ERA+ for individual players. Check out step 3 in the park factor glossary.
dan
This is an excellent illustration of the source of my confusion. It seems that many of these figures are not accompanied by an explanation of the formula/theory used to calculate the park factor and the numbers do differ from one source to the next.
It seems strange to me that there could be a pitchers park factor that differs from the hitters. It appears as though they are trying to make an adjustment for the home players not facing their own pitchers but it's counter intuitive that this would be a different number.
It appears as though there will continue to be new theories and formulas presented with time.
Any thoughts on which formula is most accurate or strengths/weaknesses of the different theories?
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] Basically, what's the significance of these figures, and can they be used in any meaningful way to predict results going forward?
