The midfielder is now back with Ajax.
Brands pointed out Klaassen as one player who found it "very difficult" in England.
"I remembered him as the absolute top. We saw him at PSV as a very good player who you would want to have in your team immediately, but he had it very difficult in England.
"I think it also has to do with what type of player you are. The Dutch players generally have good technical and tactical ability, but physically we are a little less. That is something important that you need to develop to to survive in the Premier League."