Notre Dame has done that since Kelly took over. The class of 2010 brough Louis Nix III, Prince Shembo, Bennett Jackson, and Danny Spond; 2011's haul included Stephon Tuitt and Ishaq Williams; and 2012's KeiVirae Russell is starting at cornerback. Te'o is great, and a legitimate Heisman candidate despite his value being hard to gauge, but he's one of only four seniors starting for the Irish on defense (Kapron Lewis-Moore, Dan Fox, and Zeke Motta are the other three), evidence that Kelly's staff has restocked a cupboard that has been bare for years.
Meanwhile, Notre Dame's finest defensive recruiting prize of the Kelly regime, five-star 2011 end Aaron Lynch, is already gone from South Bend, having fled to USF to get closer to his Gulf Coast home. And Notre Dame's best crop of defenders under Kelly may be the one coming in 2013, when Jaylon Smith and Alex Anzalone make it to campus.
By contrast, the other side of the ball is almost all holdovers from Charlie Weis' time at Notre Dame: the only sophomores (these would be players almost fully recruited by Kelly et al.) with major roles are Everett Golson and George Atkinson, and the line and receiving corps are almost entirely seniors. Kelly inherited his offense; he and Diaco and his recruiters built the defense, which is better than the offense is.