I think that he's over at the knee because he desperately needs a trim, not due to terrible conformation. IMO, he's not too straight in the back pastern, though. I've definitely seen a lot worse. I think he might be slightly straighter than average, but not to a problematic degree. Might warrant a little extra attention during a PPE, but not a deal breaker IMO unless the vet finds something. I'm not a conformation expert, though.