Firstly they need to have numbers, and the support of a very good band of mares...so that looks to be a stallion at one of the big stallion stations. It also helps if the yearlings in big numbers then go to a skilled trainer and they perform as 2yo's to keep the mares coming to the stallion.
I'm thinking A RocknRoll Dance fits the criteria, and with pedigree and performance credentials to back it up.
And....If I'm correct, Rasmussen Theory through the mare Wendymae Hanover