Barr’s story line embodies both the passion for change and the frustration so many feel about how to actually generate it in “Baltimore Rising.” His enthusiasm in trying to arrange a football game between Baltimore City Police officers and residents of Penn North in the film might seem misguided to some viewers given far more significant matters like another soaring homicide rate, the Department of Justice findings of widespread racism in the department and federal racketeering charges against detectives in a so-called elite unit. And, in some ways, it is. But you have to start somewhere in the process of police-community reconciliation — trivial as that somewhere might be given the troubled history of the police and their relationship to minority citizens of Baltimore.