We're in the early days on this, but it certainly isn't clear right now how they made that determination.
Is it really ever clear how that make any determination? This really makes google look bad. This is pretty much them admitting that panda did not work. Panda was targeted at low quality sites, right? Then why were these low quality sites ranking post panda? Are they saying that having an exact match domain was an exception even though you had a low quality site?