He is back to peak level but different as he ages. He plays the big match better and maintains intensity better. He is never going to have same firepower as 2011 as he lost weight but it doesn't mean much for his game.
Powerful forehand doesn't mean good forehand. Djokovic's forehead is way underrated. It's all about depth and consistency. You don't win 14 majors without top notch forehand. I say he is top five all time. Delpo's forehand not even close.