“I think now he’s found a bit of confidence, consistency and understanding of how we play, he’s getting the rewards, which is great.
“But he’s still a young guy and we bought him with very much an eye that whatever he does this year, there’s definitely a lot more in him.
“And when you see improvement that encourages us even more because it makes you think that if we invest the time in him even more, he’s going to be a super player for us.”
Johnson’s midweek effort was not enough to fire Tottenham to victory at West Ham, with the hosts able to claim a point after Kurt Zouma scored from a corner.
Spurs have conceded 10 goals from set-pieces in the Premier League this season, but Postecoglou rejected suggestions it has become an Achilles’ heel for his team.
He added: “I think we’ve been pretty good at set-pieces.
“Every goal you concede is down to something. It was a decent delivery the other night, they’ve got some big guys and the rest of the set-pieces I thought we handled quite well.
“We gave away too many corners. That was an issue for us. When you do it against a team like West Ham, who are such a big team physically. They’ve got such great deliveries with (Jarrod) Bowen and (James) Ward-Prowse — you’re asking for trouble.
“I thought that was part of the game we could have handled a bit better, not to give away so many, but I think those kind of things people just kind of look at in snapshots.
“Our winning goal against Luton came from a defensive corner. With all these things, I tend to take a longer-term view on them and for the most part I think we’ve been pretty decent.”
Spurs will be without Richarlison (knee) for this weekend’s visit of Forest.
