Just read his follow on tweets and he really is just guessing randomly...lol..
@draginol So what do you know about the PS4's API and how it compares to DX12? And is PS4's API also not fully utilizing the cores?
Brad Wardell @draginol 1h
@cozomel74 I'm afraid not. The PS4 hardware is substantially better overall though.
It's just all just speculation... just shows how even a little speculation is getting press, which just shows how much the performance gap is a problem for MS.