Questions surround defensive backs

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Todd McShay breaks down the cornerbacks and safeties invited to this year's NFL scouting combine and ranks them heading into the event. To see this and more, become an ESPN Insider.

As NFL teams prepare for the upcoming scouting combine, there appear to be more questions than answers regarding the 2009 crop of defensive backs. For starters, Malcolm Jenkins of Ohio State is the top cornerback prospect, but there's still debate regarding where he fits best in the NFL. Jenkins is at his best in space, where he can keep the play in front of him, read the quarterback's eyes and get an early break on the ball. He is not as fluid and crisp when changing directions in man-to-man coverage, which is why he is best suited to play either cornerback in a Cover 2-heavy scheme or free safety in any other scheme.

Many of the top cornerback prospects in this year's class aren't seniors, which only increases the anxiety of scouting departments across the league. With no all-star games to evaluate them in and no official measurables previously taken, NFL scouts are eager to get an up-close-and-personal look -- particularly at projected first-day picks such as CBs Vontae Davis (Illinois), D.J. Moore (Vanderbilt), Sean Smith (Utah) and Asher Allen (Georgia), each of whom brings a different skill set to the table.

Davis is a speedster with good size, but his inconsistency in coverage is tough to overlook. Moore is undersized, but he is one of the most fluid and versatile athletes in the class. Smith is a big corner with good straight-line speed but limited fluidity. And Allen is quick and tough but lacks ideal size and has marginal ball skills.

Four other possible first-day cornerbacks hail from the senior class. Of them, Alphonso Smith (Wake Forest) and Darius Butler (Connecticut) lack ideal size but are very fluid in man-to-man coverage. Butler is too much of a finesse corner, but Smith isn't afraid to mix it up in run support, which is why Smith could sneak into the last few picks of Round 1. The other two are Cary Harris (USC) and Jairus Byrd (Oregon), a pair of good-size corners best suited to playing in zone-heavy defensive schemes.

The unofficial honor of first safety selected in 2009 is still very much up for grabs, which speaks to the lack of elite talent at that position. In fact, this should be the first draft since 1999 to see the opening round come and go without a safety being selected. That's the bad news. The good news, however, is that several quality safety prospects will be available in the second and third rounds.

Louis Delmas (Western Michigan), Rashad Johnson (Alabama) and Patrick Chung (Oregon) lack ideal size, but they're instinctive playmakers who support the run harder than their measurables indicate. Kevin Ellison (USC) and Michael Hamlin (Clemson) are big and instinctive but limited athletically, which is why both have much to prove at the upcoming combine workouts. Finally, Chip Vaughn (Wake Forest) and William Moore (Missouri) should stand out in Indy thanks to their impressive combination of size and straight-line speed, but neither plays with the discipline and recognition skills necessary to stand out at safety in the NFL.

Finally, there are always a handful of quality small-school defensive backs who turn heads at the combine. Although this year's group doesn't boast any first-day talent, there are plenty of mid-to-late round DBs to monitor. Leading the list are CBs Domonique Johnson (Jackson State) and Don Carey (Norfolk State). Johnson is tall and blessed with excellent speed, but there are concerns regarding his ability to find the ball in the air when covering man-to-man. Carey is less fluid, but he's a big hitter with the potential to contribute in a zone-heavy NFL defensive scheme.