Posted by ESPN.com's Adam Rittenberg
Who needs to step up for each team?
Donsay Hardeman, S, Illinois -- Neck surgery sounds pretty scary, but Hardeman likely will return to the field this fall after undergoing the procedure during the offseason. He can provide experience at the all-important safety spot after recording 44 tackles, an interception, a forced fumble and a fumble recovery last fall.
Deonte Mack, DT, Indiana -- Any number of players could fit in this spot for the injury-plagued Hoosiers, but Mack, who missed spring ball following hip surgery, must provide leadership at an extremely thin position. Pass-rushers Greg Middleton and Jammie Kirlew will only be effective if opponents have to worry about the interior line.
Tony Moeaki, TE, Iowa -- It's hard not to pull for Moeaki, a heralded prospect who has endured injury after injury with the Hawkeyes and was on crutches during spring ball. He's expected to return this summer and possibly fill a key role after Iowa lost first-team All-Big Ten tight end Brandon Myers.
Jonas Mouton, LB, Michigan -- Michigan's improvement on defense must start with the linebackers, and Mouton returns to the mix after shoulder surgery kept him off the field this spring. Mouton finished second on the team in tackles last fall (76) and could form a solid linebacker tandem with Obi Ezeh.
Jeremy Ware, CB, Michigan State -- One of several contributors in the Spartans' secondary to miss spring ball with injuries, Ware will be a key name to monitor during the summer. He emerged nicely last season, recording an interception and six pass breakups.
Eric Decker, WR, Minnesota -- Decker wasn't hurt this spring, but he spent the time playing center field for the Gophers' baseball team. There's little doubt he's one of the nation's best receivers, but he must absorb a new offensive system installed this spring and re-establish rhythm with quarterbacks Adam Weber and MarQueis Gray.
Corey Wootton, DE, Northwestern -- How Wootton recovers from ACL surgery could shape Northwestern's defense this fall. The All-Big Ten selection missed spring ball but is ahead of schedule on his recovery and expects to practice this summer. With questions on offense, the Wildcats need Wootton to return to top form.
Dane Sanzenbacher ,WR, Ohio State -- A projected starter in the slot, Sanzenbacher missed the latter part of spring practice with a high ankle sprain. He might be Terrelle Pryor's most dependable target heading into the fall, so a strong summer will be vital for the junior.
A.J. Wallace, CB, Penn State -- The secondary remains the biggest question mark for Penn State, and Wallace can ease some of head coach Joe Paterno's concerns with a strong preseason camp performance. Hamstring problems once again slowed Wallace this spring, but the Lions sorely need his speed in pass coverage.
Jaycen Taylor, RB, Purdue -- Taylor has by far the most experience of any Boilermakers running back, so his return this summer from a torn ACL looms large. Ralph Bolden put himself in the mix for the starting job with a stellar spring, but Taylor gives new head coach Danny Hope with a proven ball-carrying option.
Louis Nzegwu, DE, Wisconsin -- Unlike a year ago, the Badgers avoided many major injuries this spring, but they'll certainly be watching Nzegwu during the coming months. The immensely gifted sophomore improved his body and impressed the coaches early on during spring ball until sustaining a torn MCL on March 31.