I think that we need to have an assessment of the linebackers as they are presently constituted before we start wanting prospects. As it stands right now they are all set inside with the will and mike in addition to two good sub guys. At um, flanker, they have the sam in Cunningham and two decent enough sub guys in Nink and TBC. Moore is a nice hand in the dirt/Sam hybrid. What they are missing is the jack/joker/whatever you care to call it which is the weakside or right OLB. This is typically the best athlete on the defense in the 34, and is less about weight and stoutness and more about length and explosion. That being identified, it reduces the need for and probability of taking a Kerrigan or converting a more classic 43 end.
So in looking at that we're basically left with three high level choices that are fits. Smith, Quinn, and Houston all fit the mold that is required for the Jack. Length to take on tackles in slide protections and to clog passing lanes (a HIGHLY underrated attribute, btw, and one I feel more valuable than explosion and counter moves), the explosion to force deep steps from linemen, the agility to drive laterally against bubble screens and quick tosses, and the hips to settle and drive from zones. Obviously, higher level skills such as countermoves, pass coverages nuances such as hand pulls and invisible jersey pulls, awareness, and snap cadence identification matter as well but it's really hard to ID those accurately.
While all three players mentioned have holes in their game and relative fit, it basically comes down to Smith and Quinn on the explosion front, and Houston in the linebacker one. Smith and Quinn have highly limited tape, Houston's work ethic concerns frighten me but I generally like his game. I'll hold off judgement until I see some linebacker drills to evaluate hips and footwork, but right now it's a total crapshoot.