There’s something to the idea that the 4th season of The Wire is the best that television can get (something, not a lot; first season of Twin Peaks is untouchable). Nothing wrong about what came before or even after, but in season four everything adds up in a perfect way.
And you don’t even see McNulty all that much. You get to see him in the priceless recurrent pub scene featuring The Pogues’ “The Body Of An American”, but he is pushed to the fringes. This is about other characters. And mostly it’s about the writing.
And maybe about education, too. Perfect subject matter for the series and, in a way, for the subversive, dysfunctional streets of Baltimore.