The safety market in free agency certainly has not dried up, but the money for it has appeared to. There are a number of legitimate names still available on the open market, including Pro Bowl talent, some of whom have been unrestricted free agents for the entire offseason, others having been released from a previous contract.
There is not, at least to me, any clear reason for this development, but it almost appears as though NFL teams are beginning to value the safety position to a lesser degree than they have in the past. Even the Pittsburgh Steelers were able to sign a veteran like Morgan Burnett on a contract that is valued below $5 million per season.