Wednesday, August 31, 2011

Stadium Park Factors

I've been thinking a lot about stadiums lately, and specifically how it seems like a lot of the newer stadiums are being built to favor pitchers. This strikes me as a strange phenomenon, because it seems to me that if one were to want more fans to come to a ballgame, it's a lot easier to entice them to come if the score has a better chance of being 6-4 than 2-0. Obviously teams can't completely control how their new park is going to play until it's built, but it seems self explanatory that a field with New Yankee Stadium dimensions is going to be more of a hitters park than one with the dimensions of Citi Field. I decided to take a look at the Park Factors of all 30 stadiums and compare that to how recently the stadium opened. If I was correct in my assumption, the more recent stadiums would mostly favor pitchers, in comparison to the older hitter-friendly confines of Fenway and Wrigley.

The park factors that I used are the multi-year park factors from Baseball-Reference. I decided to use just the hitters rating, although for most parks the pitchers rating is exactly the same.

The first thing I did was split the parks into 3 groups of 10 based on their opening date. This came up with 3 groups:

Group 1 - Fenway Park - Sun Life Stadium - 1912-1993 - average park factor of 100.2
Group 2 - Ballpark at Arlington - AT&T Park - 1994-2000 - average park factor of 100.3
Group 3 - Miller Park - Target Field - 2001-2010 - average park factor of 100

At first glance, not much of a difference between any of the 3 groupings. Each of the last two groupings has at least one very hitter friendly park though, with Coors Field at 118 in Group 2, and Yankee Stadium at 109 in Group 3. This method of grouping them didn't really come up with any conclusive results, so I decided to look at the parks a little differently.

I next split the stadiums into hitter friendly and pitcher friendly (with 100 being included in hitter friendly.) This came out with 17 pitcher friendly parks, and 13 hitter friendly parks. Of those 13 hitter friendly parks, the breakdown is as follows:

Group 1 - 6 teams
Group 2 - 3 teams
Group 3 - 4 teams

Pitcher friendly:

Group 1 - 4 teams
Group 2 - 7 teams
Group 3 - 6 teams

This shows that of the 10 most recently built parks, 6 are classified as pitcher friendly, so that's more than half, but still not as many as the 7 pitcher friendly parks that were built between 1994 and 2000. Still not really conclusive.

The next thing I did was split up the stadiums into only 2 groups, the 16 oldest, and the 14 newest. The reason I cut them into two uneven groups is because it seems that's what Bud Selig would want.  Not really, it's actually because the cut-off falls between Tropicana and Chase Field, which both opened in 1998. I put both of these into the older group, because it seemed like the thing to do.

In this case, the older group has an average park rating of 101.31. This is in comparison to 98.86 for the newer group. Finally a somewhat significant result. Of these newest 14, only 4 are considered hitter's parks (Yankees, Phillies, Reds, Brewers), while the other 10 favor the pitchers. This is in contrast to 9 hitter's parks and 7 pitcher's parks in the older group. So in this regard, it does appear that teams building new stadiums are leaning towards pitcher friendly parks. I don't think that this is what I would do if I was making the decision, but it seems to be trending in that direction. I'd like to take a look at attendance figures for hitter and pitcher friendly parks, but then you have a ton of other factors to consider, such as team performance and location. Perhaps someone with considerably more intelligence or free time will someday take a look at this. (Or perhaps they already have.)

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