Football coaches say defensive back and receiver are two of the easiest positions for a freshman to contribute at right away, because players can rely so much on instinct and athleticism.

On the flip side, the offensive and defensive lines are considered to be the most difficult, because of the complex schemes and assignments -- not to mention the superior strength of upper-classmen.

The Michigan football team, plugging holes along both lines, will hope its highly touted 2012 class can break that mold.

Michigan offensive line recruit Kyle Kalis (67) steamrolls an opponent, leading to a Lakewood (Ohio) St. Edward touchdown.

Cleveland Plain Dealer

Offensive coordinator Al Borges said last week freshmen could compete at any spot this fall, but named Kyle Kalis and Erik Magnuson as leaders to see the field because of the Wolverines' woefully thin offensive line depth.

“Kalis is a good player and he’s going to get a chance, just like Erik Magnuson,” he said.

Michigan is replacing two starters in All-American center David Molk and steady right tackle Mark Huyge. Senior Ricky Barnum has since moved to center, meaning the Wolverines' two biggest holes appear to be at left guard and right tackle.

Kalis is a five-star prospect out of Lakewood, Ohio, and is ranked by Rivals as that state's best player. He could eventually play tackle, but is expected to compete this fall with senior Elliott Mealer and sophomore Joey Burzynski at left guard.

Magnuson is a true tackle, and could compete with junior Michael Schofield on the right side. If he doesn't win the job -- and he's not expected to -- Magnuson likely will at least back up Schofield and left tackle Taylor Lewan, who have only walk-ons behind them right now.

Both Kalis and Magnuson come highly lauded. Problem is, freshmen offensive linemen rarely pan out, and Michigan likely would be playing them more out of need than choice.

"You have to block all these different defenses, and know what our numbering system is, what our rules are -- that’s a monster for a young guy," Borges said. "Some handle it better than others. And obviously, the ones that do are the ones that play faster.

"There’s not enough time in the day to tell you the challenges that a young player has to (overcome) to come in and play on the offensive line.”

Borges is familiar with those challenges, after he was forced to start three freshmen linemen -- Ryan Pugh, Lee Ziemba and Chaz Ramsey -- at Auburn in 2007.

A redshirt freshman, Mike Berry, started an additional three games.

Auburn went 9-4 (5-3 SEC) that season, ranked 100th in total offense and Borges resigned before the bowl game.

"I've never had that (many freshmen offensive linemen start) before, and haven't had it since -- and to be honest, I hope it never happens again," Borges said. "It's just proof if they are good enough, we'll put them in there."

Michigan's 2012 recruiting class ranked among the top 10 according to every major recruiting service, and its 2013 class currently is pegged No. 1 by Scout. Both are stocked at offensive line.

Kalis and Magnuson headline a 2012 group that includes tackle Ben Braden (Rockford) and guard Blake Bars (Nashville, Tenn.).

For 2013, Michigan already has non-binding commitments from five players who rank among ESPN's top 150 overall players. David Dawson is ranked the No. 1 guard according to ESPN, and Patrick Kuger is the No. 1 guard according to Scout.

Chris Fox, Logan-Tuley-Tillman and Kyle Bosch round out the class.

“I love recruiting here,” said Borges, who has coached at Auburn, UCLA, Boise State, California and Oregon, among others, “because it’s the best sell of any place I’ve ever coached.”

Kyle Meinke covers Michigan football for AnnArbor.com. He can be reached at 734-623-2588, by email at kylemeinke@annarbor.com and followed on Twitter @kmeinke.