It takes a bottom up approach rather than top-down, and gives you all the gory details as opposed to bird's eye view of things. I would take it as that. System is an almost useless word other than implying a "lower level" view.
"system" actually has a ton of meaning, it's just been co-opted to mean "hardware" in software circles. It means a collective object that is greater than the sum of its parts.
Maybe as opposed to a theoretical treatment? In academia, there is a dichotomy in CS research between systems and theory, which may have been what they were getting at.