Since the trainer of a thoroughbred race horse is an elemental component of its future development, the trainer's actions will be tied directly to the Potential Existence of a race horse by the law of cause and effect.
What is different today?
In the process of preparing a race horse for competition and placing it where it can win or be competitive, trainers will often maneuver horses for strategic reasons according to short and long term objectives; thus by observing closely the actions of a trainer, the astute handicapper can gain insight to a horse's Potential Existence today.
Look for signs, possible indicators of an elevated or diminished Potential Existence, examine carefully whenever something's different today. A jump or drop in class, a surface switch, an increase or cut back in distance, an equipment or medication change, a significant weight allowance or any combination thereof.
A change in jockey, better yet, a change back to the last jockey who won on the horse; even better, a leading jockey gets off another horse to ride this one. Better still, the leading jockey of the meet chooses to ride this horse in favor of some other horse which she or he rode to victory in its last race.
There may be early action on the tote board, the jockey might skip the post parade to warm up a horse before the race; depending upon circumstance, the possible signs will be as many as the vast array thoroughbred horse racing has to offer.