But keep in mind, the Lakers grew as a team themselves too. Kobe matured into a key player, Shaq was dominant from end to end, Rice brought the outside threat. And don't forget the impact of Ron Harper.
Supposedly Phil is great at managing egos and get the team going. He did that, but in the meantime, he alienated Kobe, in an unfair way, to cater too much to Shaq. SO that's why they fell apart later.
As to real-time, in-game impact of the coach, it is always 50/50. The coach needs to make the right decisions, and the players need to execute.