How Home Park Changes Affect a Player’s Homerun Totals

Minnesota's Target Field is the toughest park to go yard.

When a player moves from one team to another, it becomes more difficult to project his homerun totals for fantasy baseball.  To estimate a player’s homerun total, one of the first ways to do so is to check the Ballpark Index Rating of the park he played in last year versus the one he’ll play in this season.

Take Joe Mauer, for example.  Mauer moved from the homerun friendly HumpDome and into spanking new Target Field.  Unfortunately for Mauer, however, Mauer’s homerun total took a nosedive from 28 in 2009 to 9 in 2010.  It’s not difficult to figure out why.  Target Field, with a homerun index of 65, is the most difficult ballpark to hit a homerun in in all of Major League Baseball.

Mauer wasn’t the only one hurt by Target Field.  Michael Cuddyer saw his homerun total dip from 32 to 14.  As for Jim Thome, the 40-year-old hit 25 last year in Target Field in just 276 at bats (1 in 11).  With a body as big and strong as Thome’s, we guess a longer outfield fence doesn’t have much impact.

Let’s take a look at the 2010 Home Run Indexes of all Major League parks.  In this analysis the average ballpark is 100 so any variation above it makes it more homerun friendly and below it is a homerun unfriendly park.

American League Parks Home Run Index

National League Parks Homerun Index

Homerun Projections for Players with New Teams

Adam Dunn –  Washington to Chicago White Sox

For a homerun hitter, one place you want to move to is US Cellular Field.  It was the easiest ballpark to hit a homerun in last year.  With Dunn, the pure statistical analysis probably doesn’t make as much sense because he is a strikeout machine.  Dunn whiffed 199 times last year (35.6% of his at bats).  Moreover, a guy this big and strong hits bombs that would likely go out of any field.  Looking purely at homerun ballpark index, however, Dunn is projected to hit 29% more dingers this year and end up with a whopping 49 round trippers.

Carlos Pena — Tampa Bay to Chicago Cubs

Pena has hit 28, 39, and 31 homers the past three seasons.  A move to Wrigley Field should help him out.  Look for a 6% increase to 35 homeruns.

Dan Uggla — Florida to Atlanta

Uggla has been a very consistent homerun hitter with 33, 31, and 32 the last three years.  A move to Atlanta takes Uggla from a ballpark index of 80 to 103.  That means he should end this year with slightly more at 35.

Adrian Gonzalez — San Diego to Boston

Most people would think that Fenway is a homerun hitters paradise, but it’s really not with an index of 97.  Adrian Gonzalez, however, should be happy to leave Petco Park and should increase his total.  Look for 36 out of Gonzalez based purely on the ballpark index.

Adrian Beltre — Boston to Texas

Beltre is a tougher one to predict as his three year average has the anomoly of only 8 in 2009.  So, we used his 2010 total of 28 and project Beltre could hit 32 this year in Texas.

Jayson Werth — Philadelphia to Washington

Jayson Werth (and hot wife nominee Julia Werth) goes from a hitters park at Citizen’s Bank Park to to an average homerun hitters park to Nationals Park in Washington where it will be harder for Werth to go yard.  Werth has hit 27, 36, and 24 the past three seasons; look for 27 this year.

Adam LaRoche — Arizona to Washington

Talk about consistent.  LaRoche has been good for 25 homeruns in each of the past three seasons!  A move to Washington is about the same netting LaRoche 24 homers this year.  But, for consistency sake, let’s go with 25.

How we Figure Ballpark Index in Calculating Homerun Projections

Take the difference in the index between the two ballparks and divide by 2 and come up with a percentage increase or decrease.  Then, multiply that index times the player’s average homeruns over the past three seasons.  That will give you a guideline to start with when a player changes teams or ballparks.

Yes, we know there are many other factors to consider like playing time, position in the lineup, and league changes, but this is a starting point in analyzing the ballpark factor alone.

This entry was posted on Saturday, February 12th, 2011 at 10:17 am and is filed under 2011 Fantasy Baseball. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.