## Thursday, October 10, 2013

### NLCS Individual Game Odds

Vegas has some out and made the Dodgers a 55.6% favorite to win the NLCS over the St.Louis Cardinals. So what I've done is gone ahead and assigned individual game win probabilities to each game not necessarily based off of what my sim outputted, but more along the lines of fudging the odds of all seven games in attempt to make the 55.6% come out as the true chances of winning the series for the Dodgers. Below is what I came up with.

GameAway StarterHome StarterDodgers Win%
1Z.GreinkeJ.Kelly50%
2C.KershawM.Wacha59%
3A.WainwrightH.Ryu47%
4L.LynnR.Nolasco55%
5J.KellyZ.Greinke59%
6C.KershawM.Wacha59%
7H.RyuA.Wainwright38%

I took this set of game win probabilities and put it in a C program that played a 7 game series one million times, using a random number generator to determine game winners and losers and the odds of the Dodgers winning the series came out to approximately 55.6% of the time. You can argue that the odds for an individual game are a little off, but where you lean one game matchup for one team, you need to lean another matchup for the other team. It doesn't matter if I swap Greinke and Kershaw (Games 1/2, 5/6) in the games they pitch in, the odds still come out the same. Where it might matter is having Kershaw available to pitch out of the pen in Game #7. Either way, the Dodgers surely do not want this series to go to a seventh game.

Brian said...

Does home/away really change the odds of winning by ~9%?

You said, "You can argue that the odds for an individual game are a little off, but where you lean one game matchup for one team, you need to lean another matchup for the other team." I think the individual game odds matter when you say the Dodgers don't want it going to Game 7. If instead of 50/59 for the Greinke Kelly games, and 47/38 for the Ryu games, it was 54/55 and 43/42 respectively, then the odds during game 7 aren't really that bad. Yes it's on the road, and yes it's their worst pitching matchup, but I think the home/road differences are exaggerated. Or I could be completely wrong, and I defer to you on the gory math details!

Xeifrank said...

If you believe HFA is 4.5% then yes, the 9% number is what you should use. If you feel HFA is 4% then you would use 8%.

What I didn't take into consideration is the possibility that the Dodgers pitch Greinke and or Kershaw on three days rest and maybe turn Game #7 into an "all hands" on deck start. So there is actually more than one way to do this.

The main exercise is to massage the odds for the seven games, all while giving realistic game odds and having the chances of the Dodgers winning the series come out to Vegas' 55.6% number.

The 55.6% comes from the Vegas line of -135/+115 that I pulled from 5Dimes this morning.
Odds = 125/225 = 55.6%

Brian said...

Yeah sorry, I know it wasn't the main point of the article but it just stood out to me that HFA is that important. Just looked up the numbers for 2013 and it came out to 3.8% so I guess 4.5 isn't far off.

But yes, to the point of the original post, it's pretty cool to use the Vegas odds like that. And yes, things look bad for a game 7 as far as the Dodgers are concerned.

Anonymous said...

Why did you have to run a simulation when the series odds can be calculated in a fairly simple closed-end formula (using the individual game odds)?

j holz said...

Good stuff, but surely if you're going to this much effort you can find a more accurate line than 20 cents.

Xeifrank said...

Anonymous: Can you make me an excel spreadsheet (maybe Google doc) that has this simple formula, so I can change the odds then see the chances for each team winning the series?

j holz: It is accurate enough for what I am doing. 5cent, 10cent, 20cent vig, I just split the middle with it and use that as the true odds.

Anonymous said...