Since first moving to heavyweight, I've been saying that Haye's best shot at beating a Klitschko is against Vitali (which isn't to say he has a great chance)
Wlad's too cautious, controls range better, and is quicker than his brother. And his chin's not a problem if it doesn't get hit. Even if it does get touched, the fighters who have troubled Wlad's chin have done so by pressuring and landing consecutive punches. Haye never looked likely to be able to do that, and since I didn't expect Wlad to crumble the first time Haye landed a solid single shot on his chin I really couldn't see how Haye could beat Wlad.
But Vitali on the other hand is easier to hit than Wlad, especially now. Haye's footspeed and general athleticism could be more of a factor against Vitali, who looks to be slowing down and has for a while.
Having said that, Vitali has a bit more offensive variety than his brother and will certainly be more aggressive, so when considering Haye's chances the positives of course have to be weighed against the risks.