You never know who is going to cut it at Safety. Dixon, Gerry, Cooper, H Jackson, and Singleton could easily not understand their responsibilities at Safety and get moved. This is why we didn't recruit hard at this position.
Safety is the right side of the brain on defense. Linebacker being the left side. Safety makes the changes in the secondary, making calls on coverage, whether to press and what player should cover what and also be accountable for the run/play action/pass.