04/27/2009 11:43AM

Derby Odds

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With co-favorite Quality Road now officially out of the Derby, what's the toteboard going to look like on Saturday? One of things we'll be doing in this space all week is making an odds line together, updating it amid late changes, the post-position draw and any other relevant developments. I'll take the first crack at the end of this post, then y'all should feel free to weigh in on what looks square or goofy, what prices feel too high or low, and make your case for an adjustment.

This is a line predicting how the race will be bet, not what the "fair" or proper odds are, a distinction often overlooked in these exercises. The goal here is to predict the actual prices, not to drop the odds on a 30-1 shot whose virtues you think are being overlooked.

A good first step might be to review recent Derby betting, to see how the money has been distributed in the last three races, each of which had a 20-horse field. The first chart below lists their dollar odds:

Converting those odds to percentages of the win pool yields the following restatement of those prices, which can be useful as you try to figure out where the money will go. Note that these percentages incorporate Kentucky's 16 percent win-pool takeout:

A couple of guiding points in constructing a likely set of odds:

--The 80/20 rule: The top half (10) of the field takes roughly 80 percent of the money, with the bottom 10 horses the last three years accounting for right around 20 percent. That means those bottom 10 horses, regardless of what merits you may see in them, are going to attract only 1 to 3 percent of the pool each and thus go off at over 25-1.

--The top five betting choices have taken a combined 57.6, 53.4 and 50.4 percent of the pool in the each of the last three years.

The first iteration of a line below groups much of the field into tiers rather than trying to split hairs among each longshot. My feeling is that the Big Four (formerly Big Five including Quality Road) will take a little over half the combined betting; they're followed by a quintet I've listed at 15-1 apiece; two who figure to be bet pretty close to that group, at 25-1; then the eight likely longest shots. One of the things we can tinker with throughout the week is breaking the logjams at various price points and trying to settle things like which of the five we've started at 15-1 is likeliest to be the 5th vs. 9th choice in the betting.

What might look unsusual in this first pass is the absence of any horses between 8-1 and 15-1. It's tempting at first glance to drop some of those 15-1 shots to 10-1 or 12-1, but it's hard to jack up prices elsewhere to compensate, and I do think there's going to be a huge gap from the 4th to 5th choice this year. In that respect it's a little like last year's board, where there was a big falloff from Pyro as the 5.7-1 third choice to Eight Belles as the fourth choice at 13.1-1.

Note that the morning line that comes out Wednesday will not add up to 100 percent of the pool. Morning lines adhere to odds points such as 15-1 where the linemaker is not predicting a price of precisely 15.0-1 but saying he expects the horse to go off anywhere between 15.0-1 and 19.9-1, after which the next group would be at 20-1.  

Okay, here goes. Let the disagreements begin.