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Receivers Roy Roundtree, left, and Martavious Odoms catch their breath between drills during Tuesday's spring practice.

With 13 of 15 spring practices in the books, Michigan football beat writer Dave Birkett lists his five biggest revelations and five biggest questions marks of the spring.

Top 5 revelations

QB Devin Gardner - He’s third on the depth chart and probably won’t be a major contributor this year, but the early-enrollee freshman has impressed coaches with big-time talent and a championship-caliber work ethic. He devours film, has an advanced grasp of the offense (for being on campus three months) and has lived up to his billing as Michigan’s quarterback of the future.

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Receiver-turned-safety Cam Gordon

S Cam Gordon - Michigan coach Rich Rodriguez said last week Gordon was having “an outstanding spring” after switching from receiver to safety this offseason. He’s shown good ball skills and enters fall camp as the starting free safety despite never having played a college game. “There’s no question that move has been one of the better moves we’ve probably made personnel wise,” Rodriguez said.

OLB Craig Roh - Different from Gardner and Gordon in that he was a known commodity entering the spring, Roh makes this list because he appears ready to take over as Michigan’s top pass rusher next year. He’s added about 15 pounds since last season, when he started every game as a true freshman, and gives defensive coordinator Greg Robinson the versatility he desires at outside linebacker.

CB J.T. Floyd - Cornerback remains one of Michigan’s biggest concerns, but Floyd has at least assuaged some of the fears that come with breaking in a new starter. He played in just nine games and made two starts last year as a redshirt freshman, but approached spring practice like a returning vet. Of course, Michigan doesn’t have many deep passing threats and was short several receivers this spring, so Floyd’s real test will come in September.

OG Patrick Omameh - Omameh played well in a brief cameo last year at guard and locked up a starting spot with a solid spring. Michigan should have a strong interior line next year with Omameh, center David Molk and left guard Steve Schilling. That’s good because the tackle spots remain up for grabs with veterans Mark Huyge and Perry Dorrestein and redshirt freshman Taylor Lewan in the mix.

Top 5 remaining questions

Michigan Michael Cox and Fitzgerald Toussaint work on a drill during practice on Tuesday afternoon.

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Who’s the man? - Brandon Minor and Carlos Brown graduated, Vincent Smith spent his time running with trainers, and no one else in Michigan’s stable of running backs stepped up and grabbed the starting job. Smith, coming off a torn right ACL, should be back this fall, but all signs point to Michigan going a third straight year without a feature back. Mike Shaw and Mike Cox battled inconsistency this spring. A bright spot: True freshman Stephen Hopkins should crack the playing group.

Safety dance - Cam Gordon was a pleasant surprise at free safety, but Michigan still has a myriad of questions in the secondary as it switches to a 3-3-5 defense. There’s no clear-cut starter at the “spur” position, essentially the role Stevie Brown played last year, and walk-on Jordan Kovacs looks to be the starting strong safety again. A knee injury cost sophomore Vlad Emilien valuable developmental time, and when it’s all said and done Michigan could play several freshmen. Talented or not, that’s trouble in the Big Ten.

Foot patrol - In all likelihood, Michigan will start a freshman at kicker (Brendan Gibbons) and punter (Will Hagerup) this fall. Hagerup’s still in high school, while Gibbons has failed to distinguish himself for the second straight year (he redshirted last season when Jason Olesnavage won the starting job in fall camp). “Some days we’ve kicked really well and some days we’ve not kicked very well,” Michigan coach Rich Rodriguez said. “There’s some talent there, but it’s certainly not a comfortable situation where we’re at punting or placekicking right now.”

Catch me if you can - Michigan spent most of the spring without two of its top outside receivers, Junior Hemingway and Je’Ron Stokes, who missed time with injuries. Both should be fine in the fall, but there are also depth and experience concerns at the position. Stokes has played in six career games, and two of freshmen Jeremy Jackson, Jerald Robinson and Ricardo Miller could see the field this fall.

Dirty dozen - With only 12 seniors on the team and most of Michigan’s best players underclassmen, the Wolverines will have to find leadership in unusual places this fall. Rodriguez and coordinators Calvin Magee and Greg Robinson say that hasn’t been a problem so far. Veterans like Steve Schilling, Martell Webb and Greg Banks have taken vocal roles. Still, with a quarterback battle looming and plenty of negativity around the program, strong leaders must emerge.

Dave Birkett covers University of Michigan football for AnnArbor.com. He can be reached by phone at 734-623-2552 or by e-mail at davidbirkett@annarbor.com. Follow him on Twitter @davebirkett.