Rather than grade the different areas of the Niners defense – which would all get varying degrees of A – I’m going to predict the Niners 53 man roster and depth chart. QUATERBACKS 1. Alex Smith 2. Josh Johnson 3. Colin Kaepernick Analysis: I expect Johnson to win the battle for the backup quarterback job in training camp, and Scott Tolzien to be the odd man out. RUNNING BACKS 1….