While going through my Bet Labs systems today, I came across this system:

This system is simple: take every MLB favorite of -190 or more on the road.  Since 2005, it has produced a 72.3% win rate and won bettors a little over 17 units.  Now the way that Bet Labs works is by using what is called a flat betting system.  A flat betting system means that you risk the same amount on every play.  In our case, the amount is \$100 which is our standard unit size.

But there is more than one way to bet on a game.  And for this particular system, betting one unit may not be the most advantageous.  For example, if you bet one unit on a -200 favorite and they win, your net profit is 0.5 units.  Other people might bet to win one unit.  In this case, they would bet two units on a -200 favorite and would win one unit.

Using our betting archive, I went through and recalculated the results using this method to compare to our flat betting system.  The number of wins and losses remains the same, but risking more on each play resulted in a profit of +37.2 units.  This is over 20 units more than you would have won with the flat betting system.  So why not always bet more?  Because that involves more risk, of course.

In this example, we are looking at a very successful system with a very high winning percentage.  As that percentage drops, you risk of ruin increases.  We’ll use the same sample size of 264 games that is shown in the system above and see how the two different methods perform as the winning percentage drops.  “Flat Net” is the net gains/losses by using the flat betting system.  “Variable Net” is the net gains/losses by varying your betting based on the moneyline.

Win %Flat WinsFlat LossFlat NetVariable WinsVariable LossVariable Net
70%86.9-79.27.7184.8-166.318.5
69%85.6-81.83.8182.2-171.910.3
68%84.4-84.5-0.1179.5-177.42.1
67%83.1-87.1-4.0176.9-183.0-6.1
66%81.9-89.8-7.9174.2-188.5-14.3
65%80.7-92.4-11.7171.6-194.0-22.4
64%79.4-95.0-15.6169.0-199.6-30.6
63%78.2-97.7-19.5166.3-205.1-38.8
62%76.9-100.3-23.4163.7-210.7-47.0
61%75.7-103.0-27.3161.0-216.2-55.2
60%74.4-105.6-31.2158.4-221.8-63.4

This isn’t rocket science; the more that you bet on average, the more you risk of losing if you are betting a long-term losing system.  And while this is an important as a long-term idea, it is also important in the short-term.  If your betting goes south for a while (and it does for everyone who does this long enough) and you are risking more, then your bankroll may not be able to sustain the heavy losses and have enough left to keep betting once you start to bounce back.  By flat betting, you may be sacrificing some units won but it may be the only way to keep you in the game long enough to get there.