Board Thread:Naruto Discussions/@comment-27883716-20160228121105/@comment-734582-20160228213344

Godsenju wrote: Oh my god Sage kabuto said that he was strong as hagoromo,sage kabuto=hagoromo confirmed? Except that Kabuto didn't know all that much about Hagoromo. According to the best information he had, he may very well have been as strong as Hagoromo. Except, well, Hagoromo showed up and proved he was more godlike than even Juubi Madara and clearly debunked Kabuto's statements. Kabuto probably wasn't lying.

Black Zetsu on the other hand has seen about a thousand years worth of ninja fighting, plus Hagoromo and Hamura, plus he knew of his mother. His assessment about a character's strength is fairly credible.

That being said, i don't know the exact context. He probably was refering to Itachi's power relative to the existing characters. (and so ignored people like Rinnegan Juubi Madara, Hagoromo etc. At the moment of Black Zetsu's statement they were all dead after all).