Sunday night’s news that cornerback Antone Exum tore his ACL and lateral meniscus and will miss 6-9 months was a big setback for a Hokies defense that had settled into its new roles by the end of last season and was primed for a big 2013.

That’s not to say that’s out the window. Virginia Tech still returns eight starters from a defense that, after a slow start, finished the year ranked 18th nationally in total yards, second in the ACC to Florida State.

Follow me on Twitter and Facebook.

But Exum’s absence, however long it might be, is a blow. One of the Hokies’ expected strengths next year was that all the members of the secondary were back for a second straight season in the same positions. After last year’s shuffling and the early-season growing pains that came with it, the coaches eagerly anticipated having that continuity on the back end.

Now, defensive coordinator Bud Foster and secondary coach Torrian Gray  will have to go back to the drawing board. Exum’s recovery timetable has him returning as early as late-summer or as late as the middle of the season.

Even when he returns, there’s no telling at this point how effective he’ll be. Everyone reacts differently coming off ACL injuries. For every Adrian Peterson, there are dozens of players who need at least a year to come back from a knee injury (and at this point, nobody knows the severity of Exum’s injury, so there’s a lot of guesswork involved).

Regardless of when Exum returns, Virginia Tech will need to have a plan for how it will operate without him. Here are the candidates to step into Exum’s role at cornerback, on the side opposite of entrenched starter Kyle Fuller:

– Kendall Fuller, 5-11, 189, Fr.: Might as well start with the ones most fans will want to see. The younger Fuller is the Hokies’ top-ranked recruit from Olney, Md., the first five-star caliber player Virginia Tech has had since Tyrod Taylor in 2007. He’s highly ranked for a reason and probably has the skill set to come in and compete immediately for playing time or even a starting role. Fuller can’t make it official until Signing Day in February, and even then, he won’t be able to enroll at Tech until May at the earliest. He can go through summer workouts, but his first official practice won’t be until August. That leaves less than a month before the Alabama opener. Fuller is no doubt talented, but it’s hard to tell how even someone with amazing physical skills will make the transition to college.

– Donovan Riley, 5-11, 200, So.: He came on strong and emerged as the Hokies’ No. 3 cornerback by the end of the year, although even then, his playing time was extremely limited and primarily on special teams. Riley appeared on only 22 snaps on defense, 13 of which came against Austin Peay. He did have a big interception against Florida State near the goal line in November. He might not have played much, but he’s still experienced the college game on the field, which is more than a lot of players on this list can say.

– Donaldven Manning, 5-9, 155, So.: Expected to be the No. 3 option last year after enrolling in January, Manning instead had a rough debut season. He had some offseason legal issues, didn’t play much early, was burned a couple times when thrust into action against Cincinnati because of a Kyle Fuller injury and nearly left the team in November only to stick it out and remain on the squad. Manning’s stock obviously dropped last year but he was still pegged as a player who the staff thought could be an immediate contributor. He played in seven games, got 88 defensive snaps, tops among the backup cornerbacks, and made a nice pick against Austin Peay. If he can straighten things out, it’s obviously too early to close the book on him.

– Carl Jackson, 5-9, 174, Jr.: The walk-on from Tyrone, Ga., began getting second-team reps late in the year out of necessity, with Manning’s status in limbo and Tech lacking many other options. Even then, he didn’t get any playing time, getting on the field for only one special teams play against Austin Peay.

– Davion Tookes, 5-10, 171, rFr.: He had a hamstring issue during training camp that limited his progress and eventually led to a redshirt year. The Fairburn, Ga., product probably needed it anyway, having played cornerback in high school for only two seasons. A former track guy, he’s fast — “He can fly,” director of high school relations Jim Cavanaugh said last signing day — but he’ll need to develop as a cornerback.

– Der’Woun Greene, 5-10, 172, rFr.: A former quarterback out of Portsmouth, he started out at wide receiver when he got to Blacksburg but made the transition to defense during the season. Naturally, it put him behind the curve and he redshirted.

– Detrick Bonner. 6-0, 198, Jr., or Kyshoen Jarrett, 5-11, 195, Jr.: Remember, the Hokies’ two starting safeties have cornerback experience. Both played there before making the move to safety last offseason, so in a pinch, one of them could move back. Foster and Gray shuffled things around last year to get their four best players on the field at the same time. If more safeties emerge than corners this offseason, either could be an option (although I’d guess it’s a scenario the Hokies would like to avoid). It would probably be tied to the development of sophomore free safety Desmond Frye and the health of Michael Cole, who suffered a neck injury late in the season and faces an uncertain future in football.

– Another true freshman: Kendall Fuller isn’t the only cornerback Virginia Tech expects to sign come February. The class also includes a number of players who could begin at cornerback, including Brandon Facyson, an early enrollee from Newnan, Ga., who will participate in spring drills, Cequan Jefferson from Richmond (someone that 247 Sports analyst J.C. Shurburtt is high on), Anthony Shegog from Stafford and Charles Clark from Suffolk. They’re obviously inexperienced, but so is their competition at cornerback.