Baseball over/unders

[TomCowley]

Say we have a hypothetical site whose over/under bets are always -110 on each side. The total is determined by looking at various other sites (pinnacle, betcris, thegreek, etc). If the line is getting to -125/-130 (not sure what the exact cutoff is) on one side, the total gets adjusted up or down by .5 runs.

I can get a consensus "true line" from a compilation site like sbrlines. (-120 over / EV under is a "true" -110 over/+110under, meaning taking the over at -110 is a fair bet and taking the under at -110 is godawful). How far off does the line need to be before I can bet this for value? How about if if I have a consensus line for a total .5 runs different?

[whipsaw]

It depends on the line for sure. .5 runs is worth a different amount for a line of 7.5 versus a line of 10.5.

[TomCowley]

Yeah, I really had no idea what the value of half a run was for any total. I was hoping somebody had a reasonable rule of thumb, but it looks like I'm stuck searching through archives for games with 2 different and widely bet totals.

[New001]

Check Pinny's dropdown menu to start.

[King Yao]

In my upcoming book, I have a chapter on half-run values in baseball totals. There is a slight difference when you go from an integer to a half-run or vice versa. For example, comparing the totals of 7 versus 7.5 (when the fair line is even money on the two), exactly 7 runs is scored more often when the total is 7 than when it is 7.5. This relationship holds constant as you compare 7.5 vs 8, 8 vs 8.5, etc. So, I give two rule of thumb values. One where I just use totals when it is a whole number (the first number in the chart below - sorry, but I don't know how to format it so it is easier to read), and the other where I use totals that are in the range of plus or minus a half-run around (the second number).

The data is from 1998 to 2006.
Rule of thumb values are expressed in cents.

Total 7: 31/28
Total 8: 18/16
Total 9: 24/23
Total 10: 14/14
Total 11: 19/19

[TomCowley]

Thanks! You just guaranteed one sale. Just to make sure I'm understanding correctly: If the fair total is 9, then it's an average 24c shift to go to 9.5 or 8.5. If the fair total is 8.5, then it would average a 16c shift to 8 and a 23c shift to 9?

[King Yao]

Yes, that's the right way to look at it. Keep in mind of course that there's always a margin of error to these numbers. Also, these numbers were not adjusted for the money line in the game. Its possible different extremes in the money line may have different push numbers. And lastly, remember that cents is just a shortcut, the further away from even money, the less one cent is worth. For example, if the total on 9 is over -140, don't assume that the rule of thumb means over 9.5 is worth -164, it should be worth more (in cents).