(Note: This is Part 7 of a post-spring series breaking down each of Michigan football's position groups).

There's no singular theme to why it happened. Instead, a combination of many issues — some surprising, some not.

"It," of course, is Michigan's defensive meltdown against Ohio State. Most of the surface-level blame at the time fell to the secondary, as Dwayne Haskins carved the Wolverines up to the tune of 396 yards and six touchdowns on just 30 pass attempts.

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For the Wolverines, it was a disaster of the highest order. Ohio State could've picked its score that day. Everything worked. And, for Michigan, nothing landed.

The game plan was poor, the execution was poor and on a large-scale level, Michigan's man-to-man ability against a team with better overall speed was severely exposed. The Wolverines weren't exactly slow in the defensive backfield last season, but they didn't have enough elite speed to go toe-to-toe with a team that did.

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Will any of this change in 2019? Michigan will add some elite speed to its secondary this fall in the form of possibly the fastest recruit in America. Will the group be faster overall, or at least fast enough to hang in with an elite pass offense in strict man-to-man?

Well ... ?

"Coach (Jim) Harbaugh tells me all the time, more is more," defensive coordinator Don Brown said this spring when asked why he'll sprinkle in more zone concepts this year. "Make sure you have enough answers."

Offseason reset: Secondary

Depth chart: Starters — CB Lavert Hill, senior; CB Ambry Thomas, Jr.; S Josh Metellus, senior; S J'Marick Woods, junior; Nickel Brad Hawkins, junior. Reserves — CB Vincent Gray, r-fresh., CB/Nickel Jaylen Kelly-Powell, r-soph.; CB Hunter Reynolds, junior; CB Gemon Green, r-fresh; CB Jalen Perry, fresh.; S German Green, r-fresh.; S Sammy Faustin, r-fresh.; Nickel Louis Grodman, fifth; DB Daxton Hill, freshman.

Reset: So, how much more zone, exactly?

Brown's not saying. If he tells you, he'll have to kill you. Still, you can't claim Michigan has never sprinkled in zone concepts during Brown's tenure at Michigan. On the contrary, the Wolverines have used cover-2 trap concepts since Brown got here.

Michigan also used zone checks last season a number of times, notably against teams that had some success throwing the ball quickly over the middle of the field. Michigan showed zone wrinkles in a comeback against Northwestern. It tried some zone against Ohio State, but the Buckeyes had a counter to every Michigan response. It didn't work.

This will still be a base man-to-man team. In truth, it almost has to be. The more teams wrinkle in run-pass option, the more difficult it becomes to be zone-reliant. If you back off on an RPO, teams will hammer you on the ground. The best defensive backfields in the country can cover man-to-man. And Michigan has its share of solid man-coverage defenders.

But it has to be more honest with itself in the season's biggest moments.

Michigan was overwhelmed by Ohio State's speed last season and, at times and inexplicably, the Wolverines almost looked surprised by this. U-M wasn't honest with itself with regard to the athleticism of its opponent in relation to its own. It showed. Brown and cornerbacks coach Michael Zordich weren't wrong when they pointed to a few execution issues in that game, as everything (Michigan's lack of a pass rush included) fell apart.

But the game plan in that moment has to be better. Brown has been in this situation before, of course. He has also rebounded before. He's earned that benefit of the doubt.

Personnel-wise, Michigan has a chance to be faster overall in the secondary this season. How much? We'll see. Hill is an All-Big Ten corner, he'll be fine. Is Vincent Gray, who appears to be in line to take over as the team's No. 3 corner, faster than Brandon Watson was? Ambry Thomas may be an upgrade, in terms of pure speed, over David Long (who was far from slow). Though Long was the more accomplished corner overall. J'Marick Woods is a very active run defender. But can he cover enough and show more speed than Tyree Kinnel had? And if not, does that job fall to someone who can?

Hill is the piece Michigan didn't have last season and one it can't replicate. The freshman from Oklahoma has run a verified 4.30 time in the 40-yard dash. That's elite. That'd probably be good enough to make him Michigan's fastest player the day he walks into the building. He was recruited as a safety who possessed man-to-man coverage skill. Michigan hasn't given a firm answer with regard to how it plans to use Hill, but he would fit the bill of a perfect nickel man in Brown's defense. A rover, if you will. And a fast one at that.

Part of how all this shakes out is beyond the secondary's control. Brown's reliance on man coverage only works when his pass rush lands. Michigan lost some serious juice in its front seven as Devin Bush Jr., Chase Winovich and Rashan Gary are now in the NFL. If the pass rush can't muster consistent pressure, man coverage will eventually break no matter how good it is. That, too, happened against Ohio State.

It was one game. But it was a nightmare of a game. And it'll be a question hanging over this group's head or the next six months. Right up until the final day of November.

Number: 5 of 39

Brown has coached 39 games at Michigan. His pass defense has allowed eight yards per attempt or more five times in 39 games.

Two of those have been against Ohio State (2017, 2018), a third was against Penn State in 2017, a fourth came in a 56-point win over Maryland in 2016 and a fifth happened in the 2016 Orange Bowl against Florida State — on just nine completions.

The last two Ohio State teams and the 2017 Penn State squad were the best three offenses Michigan's played in the Brown era. And his units weren't able to hold against any of them.

This is the criticism and, to a degree, it's fair. Brown's defense completely shatters mediocre-to-good offensive football teams. But against great ones? It hasn't held up.

Again: There's no singular theme to this. Some, including the fact modern football favors the offense, are beyond his control. But it's still Brown's job to figure it out.

Contact Nick Baumgardner at nbaumgardn@freepress.com. Follow him on Twitter @nickbaumgardner. Read more on the Michigan Wolverines and sign up for our Wolverines newsletter.