Solution for this year or for long term?
First off i don't think that Rocky is neccesarily undersized for a 3-4 ILB.
They are many 3-4 ILB around his same size:
Copper/Siler,
Brooking/James,
DQ Jackson(go terps!)+Barton+Maiava,
Scott/Harris
I think our ILBs are set for this season.
London will be the strong side ILB(buck) and Rocky the weak side ILB(mack).
Blades,imo, because of experience playing SAM and his short stocky frame is a natural fit as a 3-4 'buck' and would be capable back-up to London.
Henson, Robert comes from TCU where i believed they played a
3-4 and he has good size and speed and showed last pre-season that he hits with good pop i think he could step in at either spot but especially the 'mack' position.
The team was high on
Young, Darrel last year a young LB with good size and outstanding speed (4.5)
Darrel Young*|*Villanova,*ILB*:*2009 NFL Draft Scout Player Profile