Historical performance data for professional leagues (affiliated minor leagues, independent minor leagues, fall/winter leagues, and other international leagues) is provided by and licensed from 24-7 Baseball and Chadwick Baseball Bureau. It incorporates the work of many stalwart baseball researchers, including Cliff Blau, Art Cantu, Frank Hamilton, Reed Howard, Kevin Johnson, Bob McConnell, Jack Morris, and Ray Nemec, as well as members of the Minor Leagues Committee of the Society for American Baseball Research.

Perhaps most importantly, it builds upon the seminal work of Ed Washuta, who magnanimously provided the framework to make the whole thing possible.

Minor league Total Zone (Rctch&Rtz, 2005-2009) data provided by Baseballprojection.com and Minorleaguesplits.com.