I mean, have you people ever been part of a program? Any athletic success I had through high school and college was due to the sum of all the coaches. In college, I had a main distance coach, but my development and mindset towards racing was helped by the head coach of the program and by every grad assistant we had. If any part of the puzzle is removed, things are different.
Why do you think Vig has assistants around? If he really could have done it all without this guy, then there's no point to having him around.