He just had a massive useage rate. If you get the guy 20 shots he will score some points and then when his confidence is up he'll start rebounding.
But like is the knock on Daniel Johnson, using him that highly isn't going to get you wins even if he'll go for 16 and 10.
The thing is he is a really bad role player because he can't contribute in a meaningful way without that high useage rate. He can't rebound and play defense unless his offensive game is going first.
He is super slow as well and has really bad core strength, which means that when there is a mismatch and an opposing guard is caught guarding him in the post the guard usually outmuscles him out of position and he can't take advantage.
His looks in preseason when he was "dominating" were mostly just bank shots from the block. But the point was that he was making a few shots, which means that his confidence was up, which means that he starts rebounding and playing defense, which then means that offense feeds off of that in a reciprocal manner.
His career isn't over, there is still potential there, if only because he is 7 foot and can walk, talk and chew gum. He just needs to hit the weight room HARD. If you're that good you can earn a paycheck by just using up your five fouls every game and grabbing a few boards.
Here is a seven footer that has played 3 NBL seasons and hasn't dunked it once. Don't forget that. Not once.