Coors Field: Bandbox no more
Posted by Andy on August 9, 2007
I was talking with a friend today when we got onto the subject of Coors Field, and how its park effects have changed. These have been well documented elsewhere, and the park effects are calculated for such things. (The Hardball Times, as well as their THT Annual, are my choices for such info.)
But, just using some of the basic info available here on B-R.com, let's see what we can learn.The increased numbers, especially of home runs, were talked about ad nauseum when Coors Field first opened. Then we all heard about the humidor, as well as some of the changes made to the park dimensions over the years.
First, let's take a look at the HRs hit by the Rockies team both at home and on the road since they got started. This is a simplistic analysis, but it is a quick way of getting a good idea what's happening.
Year Home HR Road HR Difference -------------------------------------- 1993 77 65 +12 1994 59 66 - 7 1995 134 66 +68 1996 149 72 +77 1997 124 115 + 9 1998 111 72 +39 1999 144 79 +65 2000 112 49 +63 2001 128 85 +43 2002 97 55 +42 2003 117 81 +36 2004 111 91 +20 2005 82 64 +18 2006 75 82 - 7 2007* 62 43 +19 * through Monday's games (52 home games, 59 away games)
Taken in a rough sense, you can see that in the last few years, the huge disparity has been largely eroded. There are a whole bunch of reasons why you shouldn't read too much into these numbers, including:
- This chart implies something totally wrong, namely that the other parks haven't changed. But they have. For example, Jack Murphy stadium was replaced by Petco Park, and the Rockies play a lot of road games there.
- The players have changed a lot, and the sample size is not all that large.
- Remember that the 1994 and 1995 seasons were strike-shortened. In 1994, they played 57 home games and 60 away games.
- I also believe that for west coast teams particularly, travel schedules matter a lot. The Rockies, being fairly remote to just about all other teams, put on a lot of miles, and players might be more tired some years than others.
- The Rockies have tailored their team differently at different times. It's also been seen that Coors Field allows a ton of singles, and therefore when at home, players might be trying more to hit singles and doubles. It's impossible to know about these things, but such factors do exist.
Also keep in mind that in 2007, they are already 19 homers ahead despite having played 7 more road games. If their current rates keep up for the rest of the year, they'll finish +37 HR at home.
Another interesting item is to look at the total number of hits hits by the Rockies both home and away:
Year Home HR Road HR Difference -------------------------------------- 1993 843 664 +179 1994 579 519 + 60 1995 794 612 + 68 1996 997 610 +287 1997 912 699 +213 1998 929 711 +218 1999 955 689 +266 2000 964 700 +264 2001 948 715 +233 2002 867 641 +226 2003 809 663 +146 2004 846 685 +159 2005 847 630 +217 2006 789 715 + 74 2007* 523 520 + 3 * through Monday's games (52 home games, 59 away games)
Should the 2007 rates hold up, they'll finish +100 hits at home this year (remember they have played more away games than home games). Overall, you can see that although the disparity is shrinking, it hasn't shrunk as much as the HR disparity. There are lots of theories you can put forth about this, including the fact that curve balls may still curve less in the thin air, despite the humidor. To go into much more detail is the domain of folks like The Hardball Times, so I'm going to leave it at that.
Ironically, after I wrote this piece yesterday morning, the Rockies went out and clubbed 3 HR on 23 hits in a home game yesterday. These stats are not included in the charts above, and would have a significant bump effect on their home stats.