USC announced the firings of defensive coordinator Clancy Pendergast and special teams coordinator John Baxter on Saturday night. Baxter also coached the Trojans' tight ends.
"I want to thank Coach Pendergast and Coach Baxter for their dedicated service and efforts," said Helton. "However, in evaluating our team's performance this year and after consulting with AD Mike Bohn, it is evident that these changes are necessary.
"My coaching staff and I fell short of fielding a championship team. We are taking immediate steps to improve our competitiveness and meet the winning expectations of our student-athletes and fans."
USC completed an 8-5 season with a 49-24 loss to Iowa in the Holiday Bowl on Friday. The Trojans remained in contention for the Pac-12 championship through the end of November and won five of its final six regular season games, but suffered blowout losses to Oregon and Iowa down the stretch.
Friday's loss means USC dropped five or more games in five of the past 10 seasons, including the last two under Helton's leadership.
Graham Harrell signed a multiyear contract extension to remain USC's offensive coordinator amid interest from Texas earlier this month, but he'll be joined by new coordinators on defense and special teams next season.
As always, stay tuned to The Scoop for the latest.