Im thinking from my impression that Barricade is actually Prowl in deep cover. In the novel, he basically stays on the Nemesis, and doesnt really do much of anything outside of relaying communications . In the movie he is like the forward guy following the autobots. Its a good opportunity to be the spy. And what happens to Sam when he has him pinned? Why not kill him? I think he is there to keep tabs on the Decepticons. Even cops in deep cover have to commit crimes to inbed themselves deeper. And was there ever a "Police Car" decepticon? And look at Barricade's face. I see some Prowl homages goin on. What do you guys think?