The San Francisco 49ers released their first unofficial depth chart of the preseason. Since it is named unofficial and will change once the preseason starts, it is not the biggest piece of information. USA TODAY Sports via Reuters ConnectDrake Nugent Backup CenterBrett Toth was signed to fill the backup center role. Gracen Halton Has To Climb Depth ChartHalton is a rookie who has missed time. Nate Hobbs is listed as the backup slot, so he is not pushing Renardo Green in the way that Jack Jones is.