Johns has one of the greatest rugby league minds of all time. He was doing things as a half 20 years ago that is starting to become main stream now.
But as a coach he is horrendous. The thing he did as a player can't be coached. His vision, his talent can not be passed on to a kid. You either have it or don't.
He is very clinical with his kicks. And as a kicking coach he is probably the best in the business (to teach a player how to strike the ball for bombs, Punts, grubbers, banana kicks etc). we would be better suited to have our halves spend the offseason with him instead of afl clubs (where in afl the objecting is to pass the ball to a player, not try to find open space/make the ball difficult to take). When our halves kick long they drop punt it and the ball goes high, and not too far. No power on the kicks and they just float to the opposition players (giving them plenty of time to get under the ball) that is very similar to an afl kick.
If you compared it to some great kicking players like sezar and even his hooker Hodgson the kick with a very low trajectory. Which puts more power on the ball (instead of the power going to propel the kick upwards, It's focused on distance, which gives defence no time to get under it. And then it rolls on.
As a full time mentor johns is very far off ideal. His drinking, gambling and drug problems are very evident. He is a bad influence on a club. Do you really want someone like him at the club 3 days a week?
The guy had amazing talent. Will probably go down as the best all round player in the game (defence, passing, kicking, running, converting) the guy had no weakness in his game. But like I said most of what made him legendary as a player can not be taught to someone (like when the defence is sliding which is the better pass to throw). That's all instinct not something you pick up from reading about it.