he Dolphins changed kick returners and backup centers and promoted a reserve tight end in a flurry of roster moves Monday. Added to the 53-man roster: running back/kick returner Raheem Mostert, guard/center Jacques McClendon and tight end Jack Stoneburner. Dropped from the 53-man roster: running back/returner LaMike James, running back Jonas Gray and guard Sam Brenner. Gray and Brenner will return to the Dolphins’ practice squad if they aren’t claimed off waivers, according to their agents. Mostert, claimed off the Philadelphia Eagles’ practice squad, is an undrafted rookie who averaged 26 yards per return on 88 kickoff returns at Purdue, including a nation-lead 33.5 yards per return as a freshman in 2012.