True, Del Potro is 'guilty' of playing a very unique form of power pushing often, but he can also be very aggressive with his shots and even charge the net as he did for instance during the entire Olympic tournament.
He's a very tall dude with obvious movement issues, what he has going for him is the biggest (and arguably the best) forehand in men's tennis; while great, a huge FH is not exactly what you need to win a Slam in this slow court era. His brand of power pushing was a brilliant way of adapting his game to an era that doesn't favor power players at all, shows great adaptability. It's what makes him beat lower ranked players all the time even while injured, he can extend rallies and the lower ranked guys can't handle his consistent power.
Besides, I find it very interesting. You usually see players defending by running down every ball, grinding, etc... Del Potro's defending with power brand is a great change-up, not to mention he can be quite offensive too.
i don't blame del potro for playing the way he does
you adapt to the courts you play in, and also to any injury or misfortune you encounter during your career
unfortunately for him, his serve is poor for his height, and his volleys are average, also. this, combined with his movement means he'll never be a favourite for wimbledon
he has made progress on grass this year, no doubt, but you have to think that clay is what he should be focusing on after the hard courts. australia is too much of a coin flip for anyone not named djokovic or murray.
personally, i think he should try and target one of the clay masters next year, probably Rome, then carry that confidence into RG