Sports: MLB run line wagers

In the previous post I described a simple MLB data fie for 2017. In this post, I will use this data to test a potential system for identifying wagers with positive expectations of return. I am going to look at run line wagers. In these one team gets +1.5 runs added to their score and the other has -1.5 combined with their score. The odds for these alternatives vary quite a bit from game to game.

The underlying system being used is one that has over 300 potential scores for each game based on scores of previous similar games. This system will be discussed in some future posts. The process involves looking at each of the previous scores, apply the run line, and determine a win or a loss. This is done for both teams in the current game. The resulting probability of each team covering is combined with each team’s odds to assign an expected return. The expected return is stated in return per dollar wagered.

There were potentially 4,932 run line wagers on the 2,466 games in the 2017 file. The following table summarizes the results grouped by expected return ranges. (Note: The overall win percentage of the wagers with expected return above 1.00 was 51.3%. But this is a meaningless number since it didn’t account for the odds.)

The above results indicate that there does appear to be some value in using this system and wagering on those with expected returns above $1.00. If you made all these wagers, you would be making about 9 per day. That’s an awful lot. Wagering on those with expected returns above $1.05 would lower the number to about 3 per day and raise the expected return to $1.04.

The are other ways at looking at these wagers to better improve the results rather than expected return groups. Will betting those with favorite odds be better than those with dog odds? Would using the team’s location, visit or home, improve the results? And probably most significant, what would looking at other seasons show?

I’ll open a topic on Sports Book Review in the Handicappers Think Tank forum (“Run Line Wager Analysis”) to deal with some of these questions. You are welcome to make comments, raise questions, or criticisms there. Follow me on Twitter, @ole44bill, to know when I post further analysis.