The Post’s Ryan Dunleavy gives his top 10 safeties in this year’s NFL draft, based on evaluations and conversations with people around the league: 1. Caleb Downs, Ohio State, 6-0, 206  Chess piece who can shutdown cover from the slot, patrol center field, lower the boom and blitz. Extension of the defensive coordinator in terms of communication. As a true freshman, had 100-tackle season at Alabama. Human missile battling “How high is too high for a safety?” perception. 2. Dillon Thieneman,