After I watched season 1 again I have the opinion that the young boys beating up Jimmy (Bubbles CAC junkie buddy) being a catalyst for the downfall of the Barksdale empire. It's what triggered Bubs to start snitching and putting names to faces.
Bubbles putting the red hats on nikkaz broke the case, but DAngelo lettin' that thang air out in public hallways is what set the whole shyt off. There really would not have been a case if that shyt doesn't happen in the 1st place. DAngelo doesn't end up in a courtroom. McNulty doesn't sit in that same courtroom watching String, Weebay, Stink & em do what they do for the umpteenth time, and McNulty doesn't go plant that ear into his friend, the judge's ear and so on.