We're in Breeders Cup preparation season so nearly every top class race has the potential of producing a Breeders Cup contender. Each race is very different but I think there are a few decent tips based on statistical evidence that can aid you in spotting good BC contenders as they prep for the final time.
Follow the European G-1's but do not necessarily look at the winners. 8 of the last 10 European horses to win BC races were not winners in their final prep races. And 8 of the last 10 horses did not even manage to win a race past the month of August. However all of them finished well in high class races before coming here.
Focus less on the Europeans that prep here in North America and more on those who are first off the plane. Since 1996 31 Europeans have tried to win a BC race second off the plane and none of them managed it. Most of them performed significantly worse in the BC than they did in their prep race.
Closely watch the Arc De Triomphe. In the last 10 years 15 horses have gone straight from a losing performance in the Arc to the Breeders Cup. 5 of them ended up as winners and 10 of them ran in the money.
Be wary of Turf horses who enter the Breeders Cup off of a new career highest Beyer Speed Figure. Those horses are just 4 for 63 and many of them are very well regarded. Value is best found elsewhere.
Don't take horses who are winless for the year. This may seem obvious but it's pretty easy to fall into the trap and try to get some "value" from horses who have been good all year but just haven't had any breaks. Horses like Wonder Again, Six Perfections (the year she lost), Forbidden Apple, Ace and Balletto all came into the BC "0-fer" on the year and they all exited the BC in the exact same state after taking some money.
Stay away from horses who are longshots in their last prep race. Especially steer clear of horses who won BC preps as longshots. I highlighted this statistic last year and Street Sense and Thor's Echo promptly went out and made it look silly but I think the form still holds. Horses who are more than 10/1 in their last prep race generally under perform in the BC. No horse in the last 11 years has won their last prep at 10/1 or more and then won a BC race.
Instead focus on horses who fail as favorites in their last prep race. If you had bet on every horse in the last 11 years who lost their last prep race as the favorite but still finished in the money (and was not favored again on BC day) you would have made a tidy ROI of 111.20%.
Downgrade dirt prep races where the top 3 finishers are separated by a length or less. Blanket finishes are great to watch but they often signal weak races. Cat Thief and Action This day are the only recent BC winners to emerge victorious from such a prep. In general you're better off avoiding those races.
Pay special attention to dirt horses who ran at Saratoga and Del Mar. I did a more comprehensive review of this statistic earlier but the basics are that 76.4% of BC dirt races in the last 11 years have been won by horses who ran at either Saratoga or Del Mar.
Don't forget good performances. With trainers running their charges more and more sparingly it's easy to let some impressive horses fall through the cracks on BC day. Most of the favorites in the BC are horses who ran big races within a month of the Breeders Cup itself, but don't let the hype distract you from quality horses who maybe have not been out as recently. Invasor is a classic example of this. After he won the Whitney he was hot property and had the BC been run in September he would have been 3/1 at the most. But enough time elapsed from his last race and the Bernardini hype machine was making all the headlines by the time the Classic came around. Invasor did not get any worse during that time he just fell through the cracks because he was not as fresh in our minds.