He's "got a chip in his head" that makes him connect to the web and data networks and blah blah blah. How do you power the chip? What about antennas that you need to connect to these networks, where are they? Even if you do power the chip, how do you dissipate the heat the chip gives off without boiling his brain? The show also implies that computer chips are far superior to the human brain when the truth is laughably the opposite.
As mentioned, the actor is a terrible fighter as well. He kind of flails around and basically looks like he has no idea what he's doing in a fight. Compared to Jim Caviezel in Person of Interest it's night and day.