Greg Mattison dropped a bomb on the Michigan football program last month when he left his post as defensive line coach to become co-defensive coordinator at Ohio State.
It was a decision that stung many players, from returners to incoming freshmen who Mattison had helped recruit. And that -- more than changing sides in the rivalry -- is what made the move so hard for the veteran coach.
"The hardest thing, probably, was calling the players," Mattison told reporters on Wednesday, via the Detroit News, at Ohio State's signing day press conference. "Again, it's been hard everywhere you're ever at because of what you give those players and what they give you."
Mattison was in his second stint at Michigan, having first coached there from 1992-96. He served as defensive coordinator under Brady Hoke from 2011-14, then shifted to the defensive line under Jim Harbaugh.
When Ohio State coach Ryan Day offered Mattison, 69, the chance to be a coordinator, he couldn't turn it down. Mattison said Harbaugh understood.
"Coach Day called...and approached me on the job, then obviously I went and talked to the head football coach. Coach Harbaugh was great, OK. He understood I wanted to coordinate and it was an opportunity to be a coordinator, and that was what I wanted to do. Not much you're going to do about that," Mattison said.
The first time Mattison left Michigan, he wound up at another traditional rival, Notre Dame. He said "it's always hard" to switch sides.
"One thing about college football, when you leave one program and go to another, that's one of the hardest things there is," said Mattison. "You were giving everything you have to those players. You are in every minute with them trying to make them the best you can be; that's the way I've always been as a coach.
"I've always tried to say, 'I'm going to give you everything I can to make you the best you can be, now you have to give it back.' It's always difficult."
Asked if the feeling is different going from Michigan to Ohio State, Mattison said, "I don't know if it's different or not."
"I know one thing," he went on. "When I left and went to Notre Dame, that was a hard deal. When I left Notre Dame and went to Florida, that was a hard deal. One thing I can always say, I've never been one of those guys that said, 'Boy, I want to do a good job here so I can go there.' I've thought I was going to stay every place I've been for my whole life. Nothing's changed that way."
To make matters worse for Michigan, Mattison took Al Washington with him to Columbus. Washington, who had been a defensive assistant and a key recruiter for the Wolverines, will serve as Ohio State's linebackers coach/recruiting coordinator.
It's a homecoming for Washington, who grew up in Columbus and whose father played for the Buckeyes under Woody Hayes. Like Mattison, Washington said it was "a hard decision" to leave Michigan.
"When you're in a place, wherever you are, you try to be all in. It's not like a stepping-stone place/ So not only are you involved, your family is involved. It's tough, it's really tough," Washington said, via the Detroit News. "But again, you think about where you are, this is home for me. This is an unbelievable situation and program. You're excited in the same breath.
"I wouldn't put it in the easy category, but fortunate. But when you respect where you come from, when you respect the situation you were in, it's always a little more difficult."
As for his relationship with Harbaugh, Washington, who spent one year at Michigan said, "I absolutely have a ton of respect for Coach Harbaugh. He's been nothing but great for me. It was a tough decision. Throughout it all, he really respected where I was coming from. That's kind of where I'll leave that."
To replace Mattison, Michigan hired Shaun Nua, formerly the defensive line coach at Arizona State.
