The sophomore defensive end tweeted a snake emoji, implying that his former defensive line coach had betrayed him and the Wolverines defense.
Hutchinson explained his emotions on Saturday after Michigan's spring game, saying that Mattison meant a lot to him and packing up to coach with the Wolverines' rival was something he couldn't stomach.
"Coach Matty, you know, he taught me so much when I got here, and I'm not taking any of that away from him," Hutchinson said. "But you get a big feeling of betrayal. He told me he was either retiring or he's renewing his contract, so I'm like, 'Oh, OK.'
"I thought he was leaving. I was like, 'Oh, OK, whatever.' Then he said Ohio State. That kind of makes your stomach, you know, turn a little bit."
Mattison coached Hutchinson and Hutchinson's father, Chris, who was an All-American defensive lineman in the 1990s. The family has history with Mattison, so Hutchinson was upset when his coach decided to leave for the Buckeyes and further wounded by Mattison's quote calling Michigan "the team up north."
Fellow defensive lineman Donovan Jeter was also upset by the move, but he wasn't as vocal about his reaction to Mattison's decision. Jeter initially offered a no comment when asked about his former defensive line coach, but he eventually opened up as to why he was upset.
"I'm a lot less filtered than Aidan," Jeter said. "I don't want to say anything bad about Matty because I messed up a lot off the field, and he kept his faith in me. Matty could've just [been like], 'I'm done with this kid.' But he brought me along, he showed me how to play, how to stop the run, how to be a professional.
"But doing what he did, I can't. No comment. No comment."
That coaching change has left a salty taste in the players' mouths, but not every offseason move has had a negative impact.
Players are singing the praises of offensive coordinator Josh Gattis, who they say has brought a new energy to the locker room and has revitalized the offense. Gattis has brought a speed-in-space mentality and has vowed to modernize Michigan's offense.
Starting quarterback Shea Patterson said he was excited when he first found out Gattis was the new offensive coordinator, quickly read up on Gattis and had seen the impact he had at Penn State and Alabama.
"As soon as he came in, day one, just got with the installs and looked it over with him, and I just couldn't wait to get on the field," Patterson said.
Quarterback Dylan McCaffrey went as far as saying the offense needed a change, and Gattis has brought a new mindset to what it is doing.
"I'm really enjoying it," McCaffrey said. "I think we're moving at a much faster pace. I think the offense has a lot more energy. I love it. I think come season time, it gives a lot of our players an opportunity to make plays that necessarily didn't get any."
Besides bringing energy and new opportunities, bringing in Josh Gattis meant there were fewer people involved with the offense and its strategy. Coach Jim Harbaugh said the reins would be handed over to Gattis, and he would have complete control of the offense going forward.
That was a big difference from the past, when multiple coaches, including Harbaugh, had a say in what the offense looked like and what plays were called on game day.
That streamlining of duties has resonated with the players and has already made a difference in how they're learning and implementing the system.
"I think it's easier for everyone when you got a clear-cut guy, you know who the coach is," Patterson said. "In Coach Pep (Hamilton)'s defense from last year, there were so many other coaches had their hand in and input. I think you have Coach Gattis coming in, he's running it, you trust him, and let's go."