Foul Ball Rates Jumped in 1999-2000: Are Maple Bats the Reason?
The most recent updates to the historical foul ball rates (four more seasons worth of data has been added—updates to missing games and teams as well as three more full seasons) show the three foul ball increase discussed in an earlier post becoming more pronounced.
What is also interesting with the updated numbers, retrieved from retrosheet.org, is the growing difference in rates between the American League and the National League. The AL out paces the NL by .68 foul balls more per game. This is the equivalent of about 1650 more balls per season in the American League.
1999 and 2000 Account for 99% of Foul Ball Rate Increase
The updated data (the addition of about four more seasons of information) didn’t significantly change the historical 47.7 foul balls per game rate, but it does show that starting in the 1999 season and through 2000, foul rates in the AL jumped to over 48 balls per game. The frequency of foul balls in the AL leaped 1.23 balls in 1999 from the previous year which had seen a minor dip in foul ball production. The AL rate add another .95 in 2000 before appearing to level off over the next decade and a half. In a matter of just two seasons, the American League saw an overall increase of 2.18 balls per game. When 2001 is thrown into the calculations, the AL frequency jumped 2.68 balls per game in only three years. Since interleague play started, there has only been a three ball increase in both leagues, and a 2.33 balls per game increase in the AL; this constitutes a .233 increase in fouls between 1997 and 2014. These three years account for the entire jump in foul ball rates over the 10 years of data collected to this point since the start of interleague games.
READ the rest at FoulBallz.com