Breaking Down the Brisnet Prime Power Rating

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Derek Simon

March 19th, 2015

It’s no secret that, for many moons now, I have been trying to beat the game with mechanical methods of play. In large part, because I simply don’t have time to handicap like I did 5-6 years ago… nor do I enjoy the process like I used to.
It is also no secret that I have been largely unsuccessful in this endeavor.
Don’t get me wrong: I’ve found some great systems and angles — ones that, through testing, I am confident will continue to offer solid ROIs for months and years to come. But, alas, they all suffer from “Tony Romo Disease” — they don’t show up often enough to produce consistent, meaningful returns.
Still, I love the idea of a mechanical method that can, at the very least, help guide one’s wagering decisions. So, with that in mind, I decided to slice and dice the Brisnet Prime Power Rating and see if I could find any helpful wagering angles.
(Click on image to enlarge)
First, using a database of random races run from July 2012 to February 2013 at racetracks across the country, I examined the horse with the top (highest) Prime Power rating in the field. (In the Brisnet Ultimate Past Performances, the Prime Power rating and field rank is found right before the horse’s lifetime record — see California Chrome above.)
Number: 11,953
Winners: 3,972
Win Rate: 33.2%
$2 Return:  $1.75
ROI: -15.09%
IV: 2.48
Not bad. These numbers are similar to what one would expect from the post-time favorite, which gives us a good starting point. Now let’s see what happens when the top Prime Power horse goes to post as a morning-line overlay (odds greater than or equal to the morning line) or a morning-line underlay (odds less than the morning line):
Number: 2,186
Winners: 428
Win Rate: 19.6%
$2 Return:  $1.64
ROI: -17.81%
IV: 1.49
Number: 9,767
Winners: 3,544
Win Rate: 36.3%
$2 Return:  $1.71
ROI: -14.48%
IV: 2.70
While these numbers may surprise some readers, who assume that higher prices naturally mean higher profits, they are, I have found, very indicative of what happens when one looks for overlay opportunities with “obvious” contenders.
Caveat emptor applies at the racetrack too.
A horse that looks like a legitimate 2-1 shot does not necessarily offer “value” at 20-1. Rather than rushing to the window to empty one’s 401(k) on such horses, players should ask themselves a simple question: Why? Why is a horse with so many positive attributes (remember, the Prime Power rating is a comprehensive assessment of ability) being dismissed in the wagering? What is the crowd considering that the Prime Power rating is not?
Granted, some of these horses are, in fact, genuinely overlooked. I’ve witnessed numerous animals that I thought were fairly-priced at 2-1 or less pay double digits — but that is the exception, not the rule.
With this in mind, it should come as no surprise that horses with the top Prime Power rating in a race actually perform better when that rating is lower, rather than higher:

* Top prime power rating of 100 or greater.
Number: 11,294
Winners: 3,752
Win Rate: 33.2%
$2 Return:  $1.69
ROI: -15.36%
IV: 2.49
* Top prime power rating of less than 100.
Number: 659
Winners: 220
Win Rate: 33.4%
$2 Return:  $1.79
ROI: -10.55%
IV: 2.42
Moreover, horses with the top Prime Power rating that finished poorly last time out (fifth or worse) return a profit — further proof that factors esteemed by the public, i.e. a good last race, are best avoided when looking for overlays:
* Top prime power rating of less than 100.
* Finished fifth or worse in last race.
Number: 225
Winners: 74
Win Rate: 32.9%
$2 Return:  $2.03
ROI: +1.69%
IV: 2.36
Of course, there is nothing to say that these numbers will continue to hold, but I hope they illustrate both the pros and cons of a mechanical approach.
On the plus side, using the Brisnet Prime Power rating is quick and easy and, in some instances, profitable. On the negative side, all mechanical approaches suffer from one major drawback: they can only measure what was… not what is or what will be.
Nonetheless, handicappers willing to put in the time to validate or invalidate a mechanical rating might very well profit from the experience.
(Click on image to enlarge)
NOTE: Rue Saint Honore had a race-best 95.6 Prime Power rating and finished 7th in her last race on July 29, 2012.