The stable is amazingly consistent, with no dip in overall form for years. People are queuing up to have horses with him.
Many of the horses have already been in the hands of pre-trainers and put through a sifting process in schooling bumpers before being bought on behalf of a stable owner and admitted to the yard. This helps to explain his domination of bumpers and novice events.
I'd agree with clivex that some of the younger horses don't train on (So Young would be an example). In recent years the horses from his stable which win the open Grade 1s are mostly his French imports, while the ones that start out with him are less likely to reach the top when leaving the novice ranks. Florida Pearl was a big exception of course.