That is mostly a recruiting issue. It has been an issue for most of Kelly's tenure and he is nowhere close to rectifying it. As I type this--it appears ND is going down to the wire with some 2015 Safety's and will need some luck in landing them...
LB is another huge hole for Kelly in recruiting. He inherited Teo.
Too many of his LB recruits have done nothing thus far: Deeb,Randolph, Turner, Councell etc. ND needed anyone with a pulse at LB to play in the last few games and these guys still couldn't sniff the field. Onawaulu has been shaky at best.
One of ND's biggest needs in the 2015 recruiting class was to get a top flight edge rushing DE. Mission failed. Again.