Ryan Day took a major step in retooling Ohio State’s underachieving defense on Monday by hiring Michigan defensive coordinator Greg Mattison and San Francisco 49ers defensive backs coach Jeff Hafley as defensive co-coordinators.

Those hirings mean that Greg Schiano, the Buckeyes’ defensive coordinator the past three seasons, will not return. Ohio State also announced that defensive line coach Larry Johnson was promoted to associate head coach.

Mattison, 69, has been at Michigan for two stints, from 1992-96 and from 2011 through this past season. He was the defensive coordinator in 1995 and ’96 and for the first four seasons of his latest stint. He was the defensive line coach the last three years.

Mattison was on the Florida staff under just-retired Ohio State coach Urban Meyer when new Buckeyes coach Ryan Day was a graduate assistant in 2005.

Hafley, 39, worked on the same 49ers staff as Day under Chip Kelly in 2016. Hafley was defensive backs coach for the Cleveland Browns from 2014-15.

He also coached under Schiano at Rutgers in 2011 and with the Tampa Bay Buccaneers from 2012-13.

He is a native of New Jersey. He attended Siena College.

Day took over Ohio State’s program on Wednesday after Urban Meyer’s retirement became official and has worked to assemble a defensive staff to fix the problems that plagued the Buckeyes last season. Ohio State ranked 65thnationally in yardage allowed and 51st in scoring defense.

Alex Grinch, defensive co-coordinator and safeties coach last year, left Ohio State on Friday to become defensive coordinator at Oklahoma.

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