 In March 2015, the Dolphins made the biggest free agent signing of the NFL off-season; they signed defensive tackle Ndamukong Suh to the richest contract in NFL history for any defensive player.Suh's contract is for six years and $114 million ($60 million guaranteed).Two months later, in May 2015, the Dolphins locked up franchise quarterback Ryan Tannehill through the 2020 season with a contract extension worth $96 million ($45 million guaranteed).