Not surprised if Luke Walton becomes a very good coach. He was a very smart player, a hard worker, a great teammate and a good communicator. All strong traits for a player becoming a successful coach.
In terms of credit. It's hard to know. Ezeli is starting over Bogut. I don't know if that was Walton's decision or Steve Kerr's decision. It's hard to know how plugged in and how responsible Kerr is for decisions made at GSW right now. Kerr probably still is quite close to the team despite not being able to do practices and go to games. Walton is probably still just like a lead assistant only responsible for in-game coaching with Kerr handling most of the responsibilities. Plus, like others have said. Stable healthy team that was formed by two coaches (M.Jackson, S.Kerr) that just won the Championship. Easy group to coach so long as that coach doesn't try changing too many things.
Even before this, I would have considered Luke Walton a very good head coaching prospect and the job he is doing now only reaffirms that. Improves his chances considerably of getting a head coaching gig of his own next summer. I'd like to see him take over the Lakers (as rumoured). That would be nice. A home-coming of sorts. I like ex-players manage teams they have played for in the past.