Really interesting article:
A trained eye (or even a not-so-trained one) can discern when something phishy is going on with a domain or subdomain name. There are search tools, such as Censys.io, that allow humans to specifically search through the massive pile of certificate log entries for sites that spoof certain brands or functions common to identity-processing sites. But it's not something humans can do in real time very well -- which is where machine learning steps in.
StreamingPhish and the other tools apply a set of rules against the names within certificate log entries. In StreamingPhish's case, these rules are the result of guided learning -- a corpus of known good and bad domain names is processed and turned into a "classifier," which (based on my anecdotal experience) can then fairly reliably identify potentially evil websites.