The very first Stat of the Week on www.StatOfTheWeek.com looks at the easiest and toughest home run parks in baseball five years ago. Let's take a look if it's changed much in the last five years.
We'll use park indices again (as shown in The Bill James Handbook 2009). The easiest park five years ago was the park in Puerto Rico where Montreal played a handful of games back then, Hiram Bithorn Stadium. It had a park index of 181, meaning there were 81% more home runs hit there than in an average National League park.
The easiest parks now and easiest parks five years ago are:
| Now | | Five years ago |
| Chicago, U.S. Cellular Field - 128 | | Montreal, Hiram Bithorn Stadium - 181 |
| Cincinnati, Great American Ballpark - 128 | | Colorado, Coors Field - 142 |
| Baltimore, Oriole Park at Camden Yards - 123 | | Texas, The Ballpark in Arlington - 132 |
| Philadelphia, Citizens Bank Park - 122 | | Chicago, U.S. Cellular Field - 130 |
The toughest parks:
| Now | | Five years ago |
| San Francisco, AT&T Park - 80 | | San Francisco, Pacific Bell Park - 66 |
| Pittsburgh, PNC Park - 80 | | Florida, Pro Player Stadium - 79 |
| San Diego, PETCO Park - 81 | | Tampa Bay, Tropicana Field - 81 |
| Boston, Fenway Park - 81 | | Detroit, Comerica Park - 81 |
Except for U.S. Cellular Field, home of the Chicago White Sox, all the easiest parks have changed. However, Colorado was third five years ago and just misses the current top-four list placing fifth with a park index of 120. Texas is also still a good home run park with a 108 park index.
San Francisco remains the toughest ballpark in all of baseball for home run hitters. Florida (park index 91) is still a tough park for home runs, but Tampa Bay (101) and Detroit (102) have become neutral.
Note: Pacific Bell Park in San Francisco changed its name to SBC Park in 2004; SBC Park became AT&T Park prior to the 2006 season. The dimensions never changed—just the name.