Count me as one that feels Greenwood is an up and coming linebacker that would be much more productive if they didn't take him out on third downs.
Consider this. He played 2/3rds of the snaps that Junior Seau got. In that time, Seau only had 4 more quarterback hurries than Greenwood. Seau was credited with 133 tackles. Greenwood quitely got 85 tackles despite playing only on first and second down.
What I like about Greenwood is obviously the speed he has, but also the fact that he rarely blows an assignment. The guy doesn't overrun plays and doesn't take himself out of plays. He's very assignment oriented, and that may be a reason that he doesn't make as many plays as some would like. IMO, he was a more solid linebacker than Seau last year because he didn't blow any plays. IMO, Seau took himself out of a lot of plays because of his freelancing style.