Monday, October 27, 2008

On World Series Odds

We've now seen odds for five games of the World Series, which is enough to test the efficiency of some proposition bets.

For games 1-4, I used an approximate no-vig betting line near the closing price:

Game 1: Phi -101
Game 2: Phi +165
Game 3: Phi +112
Game 4: Phi +104

Games 5-7 contain the opening no-vig line for Game 5 and extrapolated odds for Games 6 and 7, based on previous game lines:

Game 5: Phi -170
Game 6: Phi +165
Game 7: Phi +165

By the way, if you want to argue that home-field advantage shouldn't be enough to move the game line from -101 to -170 with the same pitching matchup, you're preaching to the choir. Moving on...

- Based on these lines, the series line "should" have been Phi +141, which isn't far off the mid-market line of about Phi +132.
- The series breaks down thusly:

Phi in 4

Phi in 5

Phi in 6

Phi in 7


Tam in 4

Tam in 5

Tam in 6

Tam in 7


I took a few bets concerning the exact series result. I won't grade them because they were off-market lines--that's basically the only way to make money on this kind of bet--but you can see why it pays to do these calculations yourself:

Tam wins 4-3 (+650)
Phi wins 4-3 (+800)
Phi wins 4-1 (+805 and +750)
Tam wins 4-2 (+465)
WS lasts 7 games (+380)
Phi wins 4-1 (+330; bet after Game 3) - Game odds say 30.7%

Bodog also had some other props that they set terrible lines for:

Phi wins G1 and WS (+275) - Game odds say 28.6%
Tam wins G1 and WS (+225) - Game odds say 36.9%
7-game series, Phi wins G1 (+750) - Game odds say 16.9%
7-game series, Tam wins G1 (+850) - Game odds say 14.6%

For the most part, however, the books were dealing good enough lines on these props that you were better off betting individual games.

Some more exotic props included "Will the winning team clinch at home?" or point spreads like Tampa+1.5, where you won if Tampa won the series or "covered" by losing 4-3. These were only offered at a couple of books, and those books were consistent with the individual game lines.

All in all, not a bad job; only four sportsbooks--and only one big online book--contributed to the off-market lines, and the vast majority of the good bets were from Bodog.


Webmeister said...

3-Year weighted HFA:

TB: 9.85
PHI: 1.7

For a spread of 11.55

-101 = 50.25
-170 = 62.96

for a spread of 12.71

Vegas did a pretty good job on the HFA.

vr, Xei

Robert said...

Did you have big futures bets on the Rays from before the season? I'm kicking myself for not hedging mine =[

Webmeister said...

Robert, I suppose any futures bets on the Rays from before the season are hugh, right. :)

I put $20 on them to win the W.S., at 150:1 at the Stratosphere on opening day. I should've hedged the bet before the series started, but I am not a sophisticated gambler and don't really know how to go about making the hedge bet online. If it goes a 6th or even 7th game, I will seriously consider putting some money on the Phillies to win those individual games as a hedge. Thoughts?

vr, Xei

j holz said...

re: comment 1, I certainly don't think it's statistically significant to say that Philly's HFA is 1.7%. I do think it's fair to say Tampa has a higher HFA than normal given their quirky domed stadium and years of data, but assigning 1.7% to CBP is silly.

re: 2. Yes, plenty of them. I opted not to make a post this year on which futures to bet, although it was pretty obvious which teams I liked from my March posts.

re: 3. If $3000 is a lot of money to you, a hedge is probably appropriate. You're not going to cost yourself more than $50 in EV by hedging, assuming the game lines are accurate, and it'll improve your peace of mind. You can always hedge only partway.