I own two mature stallions. One proven winner on the race track and the other proven in the breeding shed. Both of these are bred very well.
A well bred stallion or mare has the potential to pass on good qualities . Period.
A show record means nothing once that foal is conceived. That foal then has to prove itself.
Every stallion champion or not has sired failures. Most of his foals will not replicate his winnings or win championships. They may however pass on the ability that enabled the stallion to become a champion.
Showing and racing are merely competitions between riders, trainers, and breeders.
The only way to prove a stallion or mare is to breed them. That is the ultimate test of a good mare or stud. Not how many ribbons they won.
If Cassius does well in training and he will be shown in sporthorse classes ,then that will help promote him. That is the only reason to show him IMO.
His conformation, breeding, and temperament are more important to me than trophies or ribbons. After 3 or 4 foal crops if nothing he sires meets my expectations then he will no longer stand here. No matter how many ribbons he has won. Shalom