Notre Dame football coach Brian Kelly is very specific when talking about what is required for a CAT linebacker in his 3-4 scheme.

The CAT, or linebacker who drops down to the line of scrimmage at times, needs to be able to take on and beat 290- to 320-pound offensive tackles.

Then on the next play, that linebacker has to be able to re-route a receiver or a tight end and play coverage.

Not an easy player to find, but Kelly said the Irish have the right guy in Darius Fleming for the demanding outside linebacker spot.

"I think just by describing what that person has to do tells you that person has to be a unique athlete," Kelly said. "Darius has that athletic ability to do those two things. There are not a lot of those guys out there."

Fleming's unique abilities allow Notre Dame to use his outside linebacker spot to gain an advantage.

"A lot of the defensive structures are to make it difficult for the quarterback to identify who's who," Kelly said. "Sometimes (the quarterback) comes out and you're in a stack front, the next time you're in a 3-4. If you can make it difficult for the quarterback to identify what the fronts and coverages are, that's a tactical advantage."