Michigan’s 2021 spring practice session started this week and it might be the most important 15-set workout program of coach Jim Harbaugh’s tenure in Ann Arbor.

He only has a short window to mold the Wolverines into something formidable prior to the preseason fall practices and, ultimately, something to be feared entering the regular season.

Harbaugh hasn’t had a head-turning team since 2016; he’s long overdue and needs another one to parade around the Big Ten in order for UM to be truly taken seriously by its league mates. Right now, the Wolverines appear to be treading water instead of racing toward the conference’s riches.

Spring football can mean a lot, or it can mean very little; it all depends on the team. The following 15 practices must be meaningful and productive for Michigan — more so than 90 percent of the teams in the country. That’s a guestimate … but still … stuff needs to get done before stuff hits the fan.

Do or die, Jim.

Do. Or. Die.

Rebounding after a 2-4 freefall is a must. Imagine the stories that would accompany such the potentially dramatic turnaround.

Spring 2021 is set to be monumental if Harbaugh correctly plays his hand.

Here’s what to look for as the Wolverines embark on yet another critical juncture.

QB: Cade vs. JJ

The QB topic will always be the hottest point of discussion surrounding Michigan football, so it’s only right to start things with the impending battle between redshirt sophomore Cade McNamara and true freshman JJ McCarthy.

It’ll be a McChallenge for either QB — they’re both roughly the same size, both harbor similar attitudes and competitive fire, and both are among the greatest prep stars from their respective states. Joe Milton entered the transfer portal, so now it’s really on between the two rising threats.

Read this column to get a better idea — there is more to discuss and there’s no sense on elaborating on the QB squabble in this piece, so go ahead and click that link!

Coaching changes 

Let’s hit on a major staff change, that of QB coach. According to reports, Matt Weiss of the Baltimore Ravens will serve as Michigan’s next QB mentor. Yes, another one. … How many is that since Harbaugh jumped aboard to coach his alma mater? All the assistants, special advisors … it’s been a revolving door.

Michigan better hope that Weiss can do something close to what Jedd Fisch did in 2016 with Wilton Speight. Weiss was a running backs coach with the Ravens, but he was previously their QB coach (2016-17) and wide receivers coach (2018). That’s a good combination for the 12-year NFL coaching veteran.

Previously with the Ravens, Mike MacDonald is now the Wolverines’ defensive coordinator, replacing Don Brown. Former TE coach Sherrone Moore is now the OL coach, replacing Ed Warinner. Ron Bellamy, former West Bloomfield HS (Michigan) coach, is now the WR coach in Ann Arbor.

Lots of moving pieces within the staff — that’ll be something to watch all season, not just in spring.

Replacing Chris Evans’ explosiveness

Michigan fans didn’t see a lot of Chris Evans in 2020, but they’ll miss his speed, agility and ability to make something out of nothing. Evans is widely considered as one of the most slept-on players of the upcoming NFL Draft — he’ll be a steal for the team that flips the switch and drafts the former Indianapolis prep superstar.

Blake Corum seems like the next logical successor. He’s incredibly quick. Will Michigan use him in the slot like Evans? Probably not — he’s only 5-8, so that poses challenges when attempting to catch the ball. However, Corum has an Evans-like burst and can certainly rip big yardage on broken plays.

Replacing transfers

Michigan is losing quite a bit due to the transfer portal, specifically running back Zach Charbonnet and punter Will Hart — both were major contributors at one time or another. Charbonnet opened the 2020 season with a monstrous 70-yard touchdown — untouched, at that — vs. Minnesota and Hart was consistently one of the best punters in the country for the past 2 seasons.

The Wolverines, who have former UM star Mike Hart as RB coach, are stacked in the backfield — so replacing Charbonnet shouldn’t be too painful. Hassan Haskins will likely be the top back heading into spring and into the 2021 season, but the Wolverines will need another sturdy carrier to lighten the load.

Worthy in the mix?

Xavier Worthy, a 4-star recruit of the 2021 class, could push for reps as a true freshman. Harbaugh has played true freshmen at receiver, so it’s not out of the realm of possibility to see Worthy on the field this season. With Ronnie Bell, Cornelius Johnson and Giles Jackson, among others, it may be difficult for the true frosh to be a top option — but he’ll likely see some action in 2021.

Does UM have enough to compete for B1G/beat OSU?

At the end of the day, this is all that matters in Ann Arbor: Does Harbaugh have enough to compete for a Big Ten title and beat Ohio State? That’s it. Nothing else matters.

Well, beating Michigan State matters, of course … but UM has only beaten OSU thrice since 2000. Will this be the year? That’s a question every Wolverines fan asks themselves around this time.