Tracking the over/under records of Major League Baseball umpires is actually nothing new. The idea, which started in the 1980s, seems to have merit. Several umpires have generous strike zones, which could favor the pitchers, whereas other umpires are known to have quite small strike zones, something which should favor the hitters.
There is no doubt that in some years umpires will have definite patterns in the results of overs/unders in the games they work. For instance in 2006, games in which Mike Everitt was the home plate umpire went over the posted total 22 times and went under just 12 times.
The key for us as sports gamblers, is to decide whether this is a trend which bears watching or if it is the consequence of random luck. The best way to do this is to observe the over/under results for umpires in consecutive seasons to see if the over/under trends continue or not.
There were 23 umpires in 2006 who saw the games where they were the home plate umpire who saw either 60% or more of their games went over the total or under the total.
What we are interested in is how they fared in regards to over/unders the following season?
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In the case of Mike Everitt, after looking at a high percentage of his games went over the total in 2006, it was a different story in 2007, as 13 of the games where he worked behind the plate went over the total and 18 went under the total. Everitt’s case isn’t distinctive, as 14 of the 23 home plate umpires saw a direct reversal of what transpired the previous year, whereas the other nine observed their trend continue.
If a gambler would have taken the 23 umpires who had a 60% ratio one way or the other from 2006 and bet on their trends to continue in 2007, you could have won 279 bets, but could have lost 283 bets.
Using the last two baseball seasons for data, it seems that umpire trends are more random occurrences than anything else, which really is not surprising. Major league players will quickly learn about umpires’ tendencies and can make adjustment, which helps negates any advantage gamblers may have from betting either over or under a certain umpires’ games.
With any sizable statistical sampling that involves one result or the other, in this case overs or unders, there will be streaks or many similar consecutive results.
If you want a simple simulation, take a coin and flip it 40 times and chart the results. If you do this on 50 different occasions, you may get heads and tails come up close to an equal number of times over the course of the 2,000 flips. However, some of the 50 samples are titled to either heads or tails. It would not be at all surprising to see some of samples leading to27 heads and 13 tails, or the other way around and mathematical odds say you are likely to have at least one run of 10 consecutive heads or 10 consecutive tails.
This statistical tilting looks to be the main cause of some umpires seeing their games go over or under an uneven number of times. Simply stated, the odds dictate that there will be some tilting to either the over or the under when such a huge sampling is taken.
There is no real advantage of charting umpires and their correlation to totals. Your handicapping should focus on the teams and the pitchers involved, and let the men in blue look after their own things.