Detective Leander Sydnor - What was the point?

I think Sydnor is, in a way, supposed to represent the viewer. Over the course of five seasons, we learn nothing about his past, his personal life, or his ambitions. He is both figuratively and often times literally a passenger in the vehicle driven by Lester, McNulty and the rest of the police crew, just as we, the audience, are.

What's interesting is that Sydnor becomes progressively more active in the show's quest for justice all the way up until the point at which he becomes the 'next' McNulty in the show's final montage. I can only assume that David Simon would hope his viewers undergo a similar progression while watching the show. During the ride that is The Wire, we, like Sydnor, witness firsthand the corruption, crime, and immorality that lays waist to Baltimore's poor. By the end of it, maybe we, too, will find ourselves bending the rules in the name of justice.

Sydnor is a call to action, a plea from Simon that you didn't just watch the show for nothing.