Ever since it was created in the middle of the 1980s, handicappers have been betting on over/under totals. Over the last decade MLB betting has increasingly factored in the home plate umpire’s effect on totals in a game. Home plate umpires have two types of strike zones wide and narrow. Depending on which type of strike zone an umpire is using can have a significant impact on the total number of runs going over or under the predicted score by sportsbooks and bookies.

A narrow strike zone is one which benefits the hitter, as the margin for error is so little, that one bad pitch could lead to a walk or a hit. On the other hand a wide strike zone is one that benefits the pitcher, because a ball that hits the outside corner and would otherwise be considered a ball is now a strike. Basically, a narrow strike zone would cause the totals to go over while the wider strike zone would cause the totals to go under.

For example in 2006, 24 umpires led by veteran Mike Everett saw 60 percent of the games they called go over the total. Everett alone had 22 of a possible 34 games behind home plate go over the total. Yet in 2007, when Everett worked behind home plate, only 13 of his games went over the total while 18 went under.

Also in 2007, 14 of the 23 other umpires who saw their totals go over in 2006 saw games go under same as Everett in 2007. Nevertheless, the other nine umpires in that 23 total, saw the results from 2007 remain the same as 2006.

When factoring in the umpires effect on totals prior to making a wager, many bettors would have won over 280 wagers in 2007 while losing 284. It appears that the influence of umpires was rather insignificant in 2007. This can be credited too batters and pitchers making adjustments to get the results they want when the specific umpire is behind the plate.