Nevertheless, Churchill Downs's starting gate will be filled to capacity on Saturday. The rules of the Derby limit the field to 20 entrants, and for the sixth straight year the race has attracted the maximum number. This is a new phenomenon. From 1985 to 2004, the Derby didn't have a single 20-horse field. The numbers reflect the sustained popularity of the event, but there is also a disturbing development that has helped create these 20-horse fields. Most trainers have stopped employing sound judgment and horsemanship to determine whether a horse belongs in the Derby.