In February, Justin Fields also was granted a waiver after transferring from Georgia to Ohio State in January.
Although Martell initially said he would stay at Ohio State and beat out Fields (and anyone else) in a battle to replace Dwayne Haskins as the Buckeyes' starter, Martell announced his departure less than two weeks after Fields arrived.
Transfer from Georgia is competing to be Buckeyes' starting quarterback.
Harbaugh: ‘We’re not going to be sending each other Christmas cards’
Michigan began spring practice this week, which means Jim Harbaugh met with reporters to talk about the state of Wolverine football.
Asked about losing longtime assistant coach Greg Mattison to Ohio State in January, Harbaugh said he was surprised but not shocked.
"He wanted to be a coordinator again and darn near doubled his salary," Harbaugh told reporters in Ann Arbor on Monday. "I don't hold that against him, but we're not going to be sending each other Christmas cards based on where he went, but that's how I feel and understand it."
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Mattison's move created waves not just because he was jumping sides of the rivalry (along with linebackers coach Al Washington, a Columbus native whose father played at Ohio State) but because Mattison had been a fixture in Ann Arbor since joining Brady Hoke's staff in 2011 when he left a job in the NFL to return to coaching Michigan.
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Veteran defensive coach wanted to be a coordinator again
Ready to compete?
Ohio State will host a 7 on 7 passing camp in Columbus on June 17.
The camp is open to any and all high school teams with participants entering ninth grade and up in fall of 2019.
After a morning instructional session, teams will play a guaranteed five games in the afternoon including a single-elimination tournament.
The deadline to register for this camp is June 3.
Players may register as a high school team or individually.
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