While the Texans prepare for the start of their offseason program, they re-signed veteran cornerback Elbert Mack on Wednesday. The players will be on the practice field Monday for phase one of their two-week conditioning program. Coach Bill O’Brien and his position coaches can’t be on the field with the players until phase two of the program. Only new strength and conditioning coach Craig Fitzgerald and his assistants can be on the field during phase one. Mack, a reserve cornerback who played on special teams last season, is entering his seventh season in the NFL, including his second with the Texans. He’ll compete with Brandon Harris, A.J. Bouye and Josh Victorian for the backup jobs behind starters Johnathan Joseph and Kareem Jackson.