The only rule is that there are no rules. Some of our most expensive freshmen are entering precisely the end game that drove their purchase: Arabian Knight (Uncle Mo) and Muth (Good Magic) cost $2.3 million and $2 million respectively, as juveniles; Prince of Monaco (Speightstown) was a $950,000 yearling. Yet the GI Kentucky Derby remains as likely to be won by a $30,000 claim like Rich Strike (Keen Ice) or, most recently, a son of the $10,000 cover Goldencents. Last week, we saluted the advent of a $2,500 yearling...