MLB Home Field Advantage

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What is the home field advantage in Major League Baseball?  This isn’t an easy question to answer, but it is an important question to ask when considering betting on baseball.  Because MLB betting doesn’t involve a point spread (there is a runline, but that is a much different story) it’s not as easy for us to establish a baseline for what home field advantage is worth.  Wins, not winning margins are more important when you are betting on the moneyline, so how can we quantify a true home field advantage to increase our winning percentage?

I started with looking at the home and away records for every MLB team over the past five seasons:

2010
Home Record: 1359-1071 (.559)
Away Record:  1071-1359 (.441)

2009
Home Record: 1333-1097 (.549)
Away Record: 1097-1333 (.451)

2008
Home Record: 1351-1077 (.556)
Away Record: 1077-1351 (.444)

2007
Home Record: 1319-1113 (.542)
Away Record: 1113-1319 (.458)

2006
Home Record: 1327-1102 (.546)
Away Record: 1102-1327 (.454)

I’ve broken these out by year so that you can see that there is not a lot of variation from year to year.  This gives us a good idea that the winning percentage for home teams each season are going to be pretty steady.  Here are the totals:

OVERALL (2006-2010)
Home Record: 6689-5460 (.551)
Away Record: 5460-6689 (.449)

Now, we have established that home teams in general win a higher percentage of their games at home than they do on the road, which is no real shocker.  It is pretty common knowledge in sports that the home team usually does have some kind of an advantage.  The key here is that we can actually take these numbers and translate them into betting lines.  For all kinds of betting oddsmakers try to split the action evenly over both sides of a game to minimize their risk and moneylines are no exception. Using this logic we can determine a standardized moneyline for home teams versus away teams based on winning expectations.  For example, to consistently make a profit betting -140 favorites you would need to win about 58% of your wagers (for those who care this is calculated by dividing your risk amount (1.4) by the sum of your risk amount and win amount (1.4 + 1.0 = 2.4)  1.4/2.4=0.583 or 58%).

What we find from our sample is that our 55% home winning percentage translates into a -120 moneyline and our 45% road winning percentage translates into a +120 moneyline, which gives us a home field advantage of about 40 “points” in terms of the moneyline.

This tells us that we should consider a 40 point difference in the moneyline between two teams with the advantage going toward the home team.  Of course you can and should consider other factors, obviously every home team isn’t listed as a -120 favorite, however, I do think you can use it to your advantage when trying to beat the lines this year.