With 10 starters returning in 2012, Ohio State's defense was supposed to be one of the best in all of college football last year.
It didn't work out that way at the start of the year, though, as the Buckeyes struggled with teams who attacked the perimeter of their defense.
As a result, Ohio State gave up an average of 400 yards per game to its first seven opponents. The tipping point for the team and head coach Urban Meyer came in Week 7, when the Indiana Hoosiers torched the Buckeyes for 481 yards of total offense on their way to scoring 49 points.
But Ohio State's defense improved dramatically over the last five games of the season, and especially in November. Over the course of the final month of regular season play, the Buckeyes' defense ranked No. 2 nationally in yards allowed, according to Ohio State's official website.
The defense that takes the field in 2013 will look a lot different than the one that made those strides last year.
The Buckeyes return just four starters on defense next year, with holes at every level of a unit that could make or break Ohio State's title aspirations.
Here are three members of the defense that will need to step up in 2013.
Noah Spence, Defensive End
Spence played sparingly in 11 games as a backup to John Simon last year, recording 12 tackles, one sack and a pass breakup in 2012.
With Simon gone, along with every member of the Buckeyes' starting defensive line, Spence will need to provide Ohio State the kind of pass-rushing ability he displayed as a 5-star high school recruit.
The soon-to-be sophomore is a projected starter in 2013, and Spence will need to come of age quickly for a young Buckeyes defense.
Curtis Grant, Middle Linebacker
Grant won the starting middle linebacker position in the offseason last year, but later lost the role after struggling the first part of the year.
Ohio State's defensive improvement in 2012 was in large part due to Zach Boren's switch from offense (where he started as the team's fullback) to replace Grant in the middle of the defense.
With Boren now graduated, Grant will have every opportunity to make the strides required to regain his spot on defense.
Grant, a former 4-star prospect, has all the physical tools be a great middle linebacker. If his understanding of the playbook and the mental aspect of the game can catch up with his physical tools, the Buckeyes won't miss their converted fullback that bad in 2013.
Doran Grant, Cornerback
Ohio State returns three members to its secondary in 2013, but Meyer will have to replace senior Travis Howard, who played in 43 games during his collegiate career, at cornerback next year.
One of the top candidates to replace Howard is Grant, who came in as an extra defender when the Buckeyes went to their nickel formation in 2012.
Grant struggled at times last year, frequently taking poor angles to the ball or missing his assignment when the team played zone. If he can't put it together, there will be a host of highly touted freshmen (4-star Eli Apple, 4-star Cameron Burrows and 4-star Gareon Conley) who will be hungry for playing time.
All recruit rankings per 247Sports.com
David is the lead Ohio State football writer for Bleacher Report. Follow him on Twitter @davidreg412.