Hm, Byrd and Bowe were both very good and both would trouble quite a few atgs - no I don´t consider Bowe an atg and I don´t think he was in another class to Byrd. Bowe was the larger man and he had skills. Bowe fought two other large guys with skills and he got a beating by both - although he won one of those fights. The difference with the Klitschkos and Bowe is that both Klitschkos prefer fighting from the outside while Bowe prefered the inside. IMO this means Bowe has an easier time with Byrd than both Klitschkos since Byrd must go into the range where Bowe is most comfortable to score. This won´t do him any good. Bowe TKO3 Byrd.
byrd could not duplicate what tubbs did (cause he wasn't as good as tubbs), going almost exactly with what bodhi said