I'm not a horse player, so I'm hoping regnis and some others could fill me in. It's my understanding two topics are in the news regarding this contest, which involves a 10K live bankroll entrance fee. The first is that due to new tax reporting rules and regs on exotic wagering, the number of W2Gs that resulted from the Breeder's Cup wagering and taxes withheld on site were dramatically reduced, even though there were many mega-longshots, which would normally have resulted in much more being withheld.
The second is an argument regarding partnerships and team play, which is technically illegal but virtually impossible to monitor or control. Participants have signed some letters requesting certain individuals be disqualified for blatantly engaging in team play. In a similar vein, the Westgate SuperBook NFL Contest has often been the source of rumors regarding large numbers of entries being controlled by a few individuals, which theoretically enables an "economy of scale" to work in the favor of the people coordinating the entries.
If anyone is knowledgeable regarding either topic, please chime in.