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A little help

Today's top sluggers often helped by home ballparks

Posted: Friday June 11, 2004 12:56PM; Updated: Friday June 11, 2004 1:33PM
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Home Cooking
Active Career HR leaders
Rk. Player HR Avg. Home
HR Index
1. Barry Bonds 674 82
2. Sammy Sosa 549 109
3. Rafael Palmeiro 535 112
4. Ken Griffey Jr. 498 107
5. Fred McGriff 492 116
6. Juan Gonzalez 434 104
7. Frank Thomas 431 106
8. Jeff Bagwell 428 91
9. Jim Thome 398 101
10. Gary Sheffield 388 102

11. Mike Piazza 371 88
13. Alex Rodriguez 358 107
Note: 100 is an average HR index for a stadium in any given season.

One of the unique things about baseball is the way each stadium has its own effect on how the game is played. A fly ball to left field at Comerica Park doesn't present nearly the danger that it does at Fenway Park, where it could carom off the Green Monster.

Could you imagine saying the same thing about football -- "that 5-yard gain at Green Bay would have been good for 8 yards in Kansas City!" -- or hockey or basketball? As coach Norman Dale showed in Hoosiers, the basket is 10-feet high in the big city just like it is in Hickory.

Thanks to advances in statistical analysis, we can measure the effect each stadium has on the game and individual players.

Let's take Alex Rodriguez, for example. By any measure he is having a fine first season with the Yankees, batting .304 with an on-base percentage of .394 and a .536 slugging percentage. But his home run total of 13 is down considerably from the three seasons he spent in Texas, where he averaged 52 bombs a year and slugged .615. At this rate, A-Rod will hit "only" 36 home runs this year.

According to  STATS, Inc., which has charted the different zones of the field for every batted ball the past few years, Rodriguez's fly balls predominantly go to center field. From 2001-03, A-Rod hit 722 balls to the outfield, with the percentages breaking down as follows: 43.4 to center field, 29.2 percent to left and 27.4 percent to right.

Yankee Stadium is no longer "Death Valley" in center- and left-center field, as it was before its mid-'70s renovation (when Monument Park was on the field of play), but it still takes quite a poke for a right-handed hitter to go yard in the Bronx. By comparison, the Ballpark in Arlington is much more conducive to hitting home runs.

According to the latest Bill James Handbook, which lists Park Factors for every major league stadium, Texas had a home run index of 132 for the past two seasons compared to 101 for New York (96 for righties). Since 100 is the average HR index, that means it was 32 percent easier to hit a home run in Arlington than Yankee Stadium for the past two seasons. Combine that information with the fact that A-Rod likes to hit the ball to the non-power areas of Yankee Stadium (center instead of right field) and you see why his power numbers are down.

As neat and tidy as that all sounds, it's too early in the season to claim any kind of reasonable sample size for A-Rod. You don't want to bet against a great player like him doing anything, even if that is becoming the first right-handed hitter to hit at least 40 home runs in the Bronx since Joe DiMaggio (46, 1937). A-Rod is no Vinny Castilla, a one-trick pony if there ever was one. (Castilla's career slugging percentage at Coors Field is .629 compared to .428 in every other park.)

Thanks to James' work, we have enough of a sample size of park factors over the years that we can make definitive statements about this era's home run hitters. Check out the list (chart, above right) of the career active home run leaders and their average park factors since 1992. (Because of sample-size concerns, I'm not counting split seasons due to midseason trades or new ballparks opening, i.e. Safeco Field in 1999.)

Here are a couple of other notes on this topic:

Mike Piazza, who ranks 11th among active career home run leaders, has played his entire career in premier pitchers' parks. From 1993-97, the Dodger Stadium HR indexes were 97, 97, 74, 70 and 90. Then he had that weird 1998 season during which he played for the Dodgers, Marlins and Mets. From 1999-03, the HR indexes for his home park, Shea Stadium, were 81, 86, 90, 106 and 85. Piazza owns the record for most home runs by a catcher despite enjoying only one season with a hitter-friendly environment as his home stadium.

* What Barry Bonds has done while playing at SBC Park is, in a word, ridiculous. Here are the HR indexes for the park since it opened in 2000: 91, 62, 54, 81.

Jeff Bagwell knows what life is like at both ends of the spectrum. From 1992-99, the Astrodome's HR index was 81. But Enron Field/Minute Maid Park was a sizzling 114 in its first four years of existence.

* It's no wonder A-Rod couldn't wait to get away from Seattle. In his only full season at Safeco Field, 2000, he hit 13 home runs at home compared to 28 on the road. The HR index for Safeco Field that season was 80. And Juan Gonzalez made a mad dash out of Comerica Park after one season with the Tigers, 2000, in which the index was 61.

Ken Griffey Jr. has played in above-average hitter's parks in all but one year -- 1993. The Great American Ball Park yielded a HR Index of 118 in 2003, its inaugural season.

* Moving the fences in at U.S. Cellular Field has had an extreme effect. From 1992-2000, the average HR index was 97. From 2001-03, with the right- and left-field foul lines shortened by 17 feet each, the index rose to 130. White Sox slugger Frank Thomas has been a beneficiary of this change, hitting 53 of his 70 home runs from 2002-03 at home.

Jacob Luft is a Baseball Producer for SI.com.