A big indictment of Gates and the LAPD is all of the talk about them from the black community in relation to the cause of the riot. Those people are not just making things up, looking for a scapegoat. They know why they are outraged.
I get the impression that the LAPD was quite a bit worse than average in areas like racial discrimination and excessive force. But even if all police departments were equally bad, the LAPD could still be blameworthy.