Johnson accepts he must start to living up to expectations.
"It's been the worst season of my career as a whole, I think," he said.
"I actually haven't been that bad on the stats side of things but performances haven't been what I've wanted.
"If you go through goals and assists, I haven't done that bad but performances have been sometimes. You look at yourself and you're honest with yourself. I think in general everything hasn't gone well.
"We've got to look forward to next season now. It's all we can do."