Mattison was lured away from Michigan by the opportunity to be a major part of drawing up the defense after having been relegated to defensive line coach when Jim Harbaugh became the head coach of the Wolverines in 2015.
The plan was for Mattison to coordinate the front with Hafley handling the back of the defense.
They kept the 4-3 front Ohio State has run some variation of since the mid 1990s but made more pronounced changes to the secondary.
Hafley brought a unique version of Cover 3 defense with him from the 49ers, where then-defensive coordinator Robert Saleh had installed the man-zone hybrid system he learned from Pete Carroll in Seattle.
When Hafley left to become head coach at Boston College, Day confirmed that bend-but-don’t-break style of defense was what he found to be the best for today’s college football.
He hired Kerry Coombs, a former Ohio State assistant who spent two years with the Tennessee Titans, to maintain it, but there was a big drop-off from year one to year two in the system.
Although Coombs coached in a variety of systems both in his first stint at Ohio State and during his time in the NFL, he had not previously run the particular version of Cover 3 developed by Carroll and spread through the league by his former assistants.
Mattison’s exit means Day could bring in someone with more familiarity with that defense to work under Coombs and assistant head coach Larry Johnson or go in a different direction and change schemes again.
“Yeah, I think both are possibilities,” Day said Friday.
He noted that the game plan against Alabama had included some variety, including Cover 2 looks and some zone blitzes, but he acknowledged a more pronounced change might be beneficial.
“It’s going to evolve,” Day said. “Anybody who has a background in a four-down (lineman), single-high (safety) defense certainly would would fit quicker, but then also bringing in somebody that has a little bit more of a diverse background can give us different perspective.”
Whatever direction he goes, Day wants to see the staff mold its strategy around the players on hand.
Among the reasons the hybrid scheme worked in 2019 was the presence of first-round NFL Draft picks Jeffrey Okudah and Damon Arnette at corner. Meanwhile, safety Jordan Fuller cleaned things up behind them and went on to be a sixth-round pick who by all accounts is having an outstanding season for the Los Angeles Rams.
All of their replacements struggled at least at times in 2020, a season that started late and was frequently disrupted because of COVID-19 protocols.
“I think (playing to players’ strengths) is what’s important because we try to do that all the time on offense, and I think that that’s going to be important on defense is based on who we have that year, what gives us the best chance to be successful,” Day said.
“And if it’s to continue to be in a single-high, Cover 3, let’s let’s do it, but if it’s not, what are the things?
“Do we want to have some continuity there and keep that going or do we want to bring in somebody with a different perspective? So (those are) all the discussions that are being had now.”