The winger is finding his feet in a Spurs shirt more than a year after moving from Nottingham Forest.
Johnson has been in a habit of scoring and continued that trend against Ferencvaros in the Europa League.
Postecoglou stated post-game: “No, (it's not) and I thought he was unlucky with the one that hit the bar as well. Look, he is in a great vein of form and obviously feels good about himself at the moment, really confident.
“I guess with all attacking players, goals and assists, they kind of thrive on that stuff, but I've said before he has been fantastic for us. Even if you look at his figures last year.
“He moved to a big club and still got a decent return of goals. It was always curious to me why people were singling him out because if you compare him to other wingers in the league, his numbers always stacked up anyway and now he has probably bypassed all of them.
“I had no doubt he would make a massive impact for us. Now he is making not just an impact but changing games for us. Again, still a young guy, still working hard and wants to learn, so that's great for us.”