I'm very interested in seeing how Spense performs in training camp when he has to fight off blockers. Is size a concern... maybe. I'd be a bit less worried if he didn't have such poor bench press stats at the combine. I know that doesn't mean all that much but wasn't it the worst amongst all LBs?
With that being said, I love what I hear about his instincts, explosiveness and "football smarts". I've watched the youtube clips and it's definitely eye opening. One he diagnoses a play (which is VERY quick IMO), he attacks the ball like he's been shot out of a cannon (Polamalu-style). As long as he can hold up at the point of attack, I think we have our ILB of the future. I do think he'll need to bulk up some though.