There are some nice defensive backfields in the Big Ten. And none is better than Ohio State?s. In fact, the Buckeyes may have the top secondary in the nation, which is one of many reasons why Ohio State is a legit national title contender. Here?s my ranking of the Big Ten defensive backfields.

1. Ohio State. Loaded. There is no other way to describe this unit, which will be led by junior Bradley Roby, who may be the top cornerback in the nation. Safeties Christian Bryant and C.J. Barnett also are returning starters. Is there a better safety tandem in America? Junior Doran Grant, who has starting experience, will man the other corner spot. Depth is lush, with players like Cam Burrows, Adam Griffin, Eli Apple, Armani Reeves and Najee Murray, among others.

[ RELATED: Check out all of Dienhart's 2013 unit rankings ]

2. Michigan State. Yes, cornerback Johnny Adams is gone. But there is still a lot of talent in the secondary. Senior strong safety Isaiah Lewis is a legit star and future pro. Redshirt freshman Demetrious Cox is another strong option at safety. Coaches think he could be special. Junior Kurtis Drummond is a steady force at free safety. Sophomore Trae Waynes emerged in the spring as a playmaker. Fellow sophomore Arjen Colquhoun also is on the rise. Senior Darqueze Dennard will be one of the Big Ten?s top corners.

3. Michigan. Strong safety Jordan Kovacs will be missed. Who will be the leader? Senior Thomas Gordon-reliable, steady and unspectacular–is the heir to Kovacs? spot. Jarrod Wilson is in line to play free safety with Gordon moving to the strong spot. Sophomore cornerback Blake Countess must show he?s OK after redshirting last season following a knee injury in the opener. With J.T. Floyd gone, junior Raymon Taylor looks like the other corner. Nickel situations will see junior Courtney Avery on the field. And keep an eye on freshman Dymonte Thomas.

4. Nebraska. This arguably is the most talented unit of the Cornhuskers? often-maligned defense. Big, physical senior Stanley Jean-Baptiste has one corner spot. Seniors Ciante Evans and Andrew Green are competing for the other slot. Sophomore corner Jonathan Rose-a transfer from Auburn–has some staffers excited. Juniors Corey Cooper and Harvey Jackson are top options at safety with Daimion Stafford and P.J. Smith gone.

5. Northwestern. Safety Jared Carpenter and corner Demetrius Dugar will be missed. Sophomore Nick VanHoose is ready to become a top cornerback. Safety Ibraheim Campbell is the other starter back. He?s a legit All-Big Ten player. Sophomore Traveon Henry looks good at the other safety spot. The corner spot opposite VanHoose could go to C.J. Bryant, Dwight White or Daniel Jones.

6. Minnesota. This has been an underrated unit in recent years. But there is work to do this year with cornerbacks Michael Carter and Troy Stoudermire departed. Standout junior Derrick Wells has shifted from safety to cornerback, his original position. Look for seniors Jeremy Baltazar or Martez Shabazz at the other corner slot. Minnesota was able to move Wells because of depth at safety, with players like senior Brock Vereen, junior Cedric Thompson and sophomore Damarius Travis.

7. Wisconsin. There is work to do with three starters gone, including corners Marcus Cromartie and Devin Smith, along with safety Shelton Johnson. The lone starter back is senior free safety Dezmen Southward. Redshirt freshman Reggie Mitchell is being counted on to start at strong safety. The corners will be new. Sophomore Darius Hillary and freshman Sojourn Shelton are in the mix at one corner spot. Junior Peniel Jean looks like the other starter.

8. Penn State. Questions abound with players like Stephon Morris and Jacob Fagnano gone. Seniors Stephen Obeng-Agyapong and Malcolm Willis will patrol the safety spots. Junior Adrian Amos is back at one corner spots; sophomore DaQuan Davis has a bead on the other corner slot. A group of talented newcomers may help.

9. Purdue. Some nice potential. Senior Ricardo Allen is coming off a disappointing season and wants to finish on a high note with fellow corner Josh Johnson gone. Allen is an undersized playmaker. Sophomore Frankie Williams teems with potential at the other corner spot. Senior Normondo Harris can play in nickel. Former walk-on Landon Feichter is a classic overachiever and tackling machine at one safety spot. Junior Taylor Richards is back after showing promise at the other safety spot in 2012. He?s physical.

10. Iowa. The unit floundered down the stretch last season. And star corner Micah Hyde is gone. The safeties really struggled late. Juniors John Lowdermilk and Nico Law and senior Tanner Miller need to solidify the spots. Redshirt freshman Anthony Gair also has a chance. Senior B.J. Lowery has one corner spot sewn up. But who has the other? Sophomore Jordan Lomax may be the favorite but is coming off injury. Fellow sophomore Sean Draper also is in the fold.

11. Illinois. Improvement is needed. And it hurts that cornerback Terry Hawthorne is gone. Fellow corner Justin Green also is gone. The lone starter back is junior strong safety Earnest Thomas. Redshirt freshman Taylor Barton is in line to start at free safety. Sophomores V?Angelo Bentley and Eaton Spence also are in the mix, along with JC Zane Petty-who can play corner or safety.

12. Indiana. This unit is improving. The safety duo of junior Mark Murphy and senior Greg Heban is underrated. Each is a savvy player with decent athletic ability. Junior Kenny Mullen is a top cornerback; senior Antonio Marshall is a bigger corner who is good vs. the run.

About Tom Dienhart BTN.com senior writer Tom Dienhart is a veteran sports journalist who covers Big Ten football and men's basketball for BTN.com and BTN TV. Find him on Twitter and Facebook, read all of his work at btn.com/tomdienhart, and subscribe to his posts via RSS. Also, send questions to his weekly mailbag using the form below and read all of his previous answers in his reader mailbag section.

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