Head football coach Clay Helton has had a penchant for hiring former assistants for his new staff, and Tuesday the trend continued as the Trojans announced the addition of Tommie Robinson as running backs coach.Robinson served as running backs coach and passing game coordinator for USC in 2013 under head coach Lane Kiffin but was not retained after Steve Sarkisian was hired.The 52-year-old has plenty of experience at the collegiate and NFL levels — 30 years in all — and he spent the last two seasons as the running backs coach for the Texas Longhorns.“We are thrilled to welcome back Tommie Robinson to the Trojan Family,” Helton said. “He is one of the most respected running back coaches in our profession. He has had an extensive career in both the NFL and college and he will pass on that knowledge to our young running back group.”Helton also worked with Robinson at Memphis, where they were both assistants in 2006.“I have had the good fortune to work with Tommie on two different occasions, at USC and at Memphis, and have seen firsthand how he develops young men both on and off the field,” Helton said. “He is a true professional and a terrific recruiter.”During the 2013 season at USC, Robinson guided the Trojans’ offense to 29 rushing touchdowns, its most in eight years.After starting his career as a graduate assistant at Arkansas, Robinson spent time at Utah State, TCU, and UNLV. Then came a three-year stint in the NFL with the Dallas Cowboys where he served as a wide receivers and special teams assistant. Prior to his first stint at USC, Robinson was the running backs coach for the Arizona Cardinals from 2010-2012.Robinson’s career has also seen stops at Memphis, Georgia Tech, Oklahoma State and Miami.Last season, the Longhorns averaged 5.67 yards per carry under Robinson, who will look to get the best out of several running backs the Trojans plan to feature, including Ronald Jones II and Justin Davis.Robinson joins Clancy Pendergast (defensive coordinator), Tee Martin (offensive coordinator), John Baxter (special teams coordinator and tight ends coach) and Helton as former assistants under Kiffin who will be on Helton’s staff in 2016. Pendergast and Baxter were brought in while Martin was promoted from wide receivers coach.Robinson’s hire means that Johnny Nansen, who was the running backs coach the last two seasons at USC, will shift to linebackers coach and recruiting coordinator. Nansen was retained by Helton after coming over with Sarkisian from Washington.