So, your NFL team has taken it upon themselves to pick up an Ohio State Buckeye, this one defensive lineman/linebacker Nathan Williams. Williams runs a 4.80s 40-yard-dash, and put up 24 reps on the bench press at 225, a 35" vertical leap and 9'5" broad jump at his pro day work out, so he has good athleticism for the position.
He is also one of the hardest working players in the draft, as evidenced by his long comeback trail from his injury in 2011. Williams' play finally caught back up to its former level closer to the end of 2012, as he finally appeared to be fluid in his movements without a hitch in his step in the last two games of the season.
Williams has always been an exciting player to watch, but has not had very many dominating games. The last truly showcase type performance for him was in 2010 against Miami and Jacory Harris, where he had multiple quarterback pressures and an interception when dropping back into coverage. He is probably best off in a 3-4 as a rush linebacker, lining up in a two-point stance where he can use his quickness to shed blocks instead of having to use brute strength to stop the run. He also showed some good coverage ability, especially in the Michigan State game on running backs such as Le'Veon Bell and even checked Dion Sims on a few plays.
You can see Williams in action here against Penn State, where his coverage skills are on display. He is quick enough to completely take away a team's checkdown option on a play-action pass, and smart enough to stay home on fakes. The other nice thing about him is that he does not quit on a play. Even if he takes a bad angle to start, he will correct it mid-play and chase the runner down. Williams plays with a lot of emotion and can be a leader on a team that needs one.
Williams can beat tackles with speed rushes, but is much better off using power against smaller tight ends and fullbacks. A larger player can simply snuff him out. The issue with Williams, as with many college defensive linemen, is that he is a "tweener" at 6'3", 241lbs. This, along with some issues with strength and durability concerns, will drop him into the later rounds where a 3-4 team should scoop him right up.
Williams' best NFL comparison is a player like Frank Zombo of the Green Bay Packers or Erik Walden of the Indianapolis Colts. He is a good player to have in your two-deep at 3-4 defensive end/linebacker. Williams should be a great value in the 6th or 7th round.