Wladimir klitschko is slaughtered for his level of opposition

Wlad does know how to use his size and length very well and is talented. The reasons he is blasted in general involves more than just opposition level, though that is a factor.

One, there are some names you failed to mention such as Pianeta, Wach, Mormeck, and Leapai. Since 2012, Wlad has had six fights(Pulev fight hasn't happened yet). Four of them were with these names. Quite honestly, that really is telling right there.

Two, style-wise, Wlad has made a habit of avoiding fighters that are punchers and/or fighters that fight on the inside. He and his brother quite frankly had a good racket where Vitali would take on the fighters with more tough styles for Wlad(Chisora, Arreola) and Wlad would take on more mobile fighters that might trouble his brother.

Three, even opponents who appear decent generally don't pass the eye test in terms of effort against Wlad. So many fighters just stay on the outside against Wlad and let him slowly break them down, displaying no desire to try and force their way inside or they just don't have the tools to threaten Wlad in any way. Wlad deserves some credit for intimidation factor but it really tells more to the poor state of the Heavyweight division.

Four, and I believe this is the primary reason Wlad is disliked, is Wlad's style. He has no willingness to engage on the inside to the point of ridiculousness and fights so timidly even against fighters that pose little threat to him like Mormeck that he doesn't help his rep at all. The few opponents that actually make a token effort to get inside on Wlad(like Povetkin) can look forward to a buffet of grabbing, body slamming, and general fouling that Wlad is permitted to get away due to friendly refs. Wlad and Haye talked a ton of crap to each other prior to their fight. Haye fought in a stupid and scared manner against Wlad. But Wlad didn't cover himself with glory trying to take Haye's head off as advertised pre-fight. He barely touched Haye and won the fight by throwing more punches(and not many at that) and keeping Haye on the defensive. He didn't land much clean on Haye at all, and made no attempt to genuinely press Haye. There's just no appeal to Wlad winning in the way that he does from the fans perspective against overmatched opposition.