klitscho is probably past his very best but he's still in fantastic shape and a very live opponent for anyone. there's still only 2/3 at most current fighters that would stand a chance against him even now.
people keep saying how bad he was against fury but that's not because he's shot or washed up, it's because he was fighting against a very effective, very big guy. klitscho likes to bully his opponents, push them around, lean on them and generally keep them off balance. he couldn't do that with fury because for once he came up against someone bigger and stronger than himself with a longer reach. who also happens to be technically very effective.
people saying klitscho didn't throw enough punches etc etc, which is very easy for an onlooker to point out. a bit harder to implement when you're in against a very awkward 6 foot 9 giant who is punishing you every time you miss.
i see him having a similar issue with joshua. he is going to find it difficult to push joshua around and what joshua lacks in awkwardness compared to fury he makes up for in power.