Frank Clark wasn't really on Michigan's recruiting radar until he gained an offer in late 2010, a few months before signing day. At the time, and when he later wound up committing to Michigan's new coaching staff in February, most thought that he would be destined to play tight end, as he was a two-way prospect that projected to play either at defensive end/outside linebacker or tight end. From the "Hello" post on MGoBlog after Clark's commitment:
Wooo! Michigan got a tight end! That was a huge need in this class, and Mr. Clark's commitment makes it less of a pressing issue. The coaching staff is still going hard after TX TE Chris Barnett [Note: Barnett wound up committing, but left Michigan without playing a down] as well. Barnett is more of a true tight end, and is probably more ready to play right away than Clark is.
Since Clark was somewhat of a late riser in the recruiting process, there wasn't much scouting info, highlight video-type stuff, or really anything that indicated what kind of player he'd be. He did have a few pretty decent offers: Michigan State, Cal, North Carolina, and Minnesota, and he did hail from Cleveland (OH) Glenville -- a school that produces D-1 talent year-in and year-out. Michigan wasn't able to recruit this Ohio State feeder very well (Ted Ginn, Sr. is the coach, after all), but Clark was the first Glenville alum to head to Michigan in years. Apparently Michigan's gotten its foot in the door, as incoming freshman DT Willie Henry also graduated from Glenville.
Michigan initially planned to play Clark at linebacker, but after he got on campus, they decided to move him down to defensive end. To the best of my knowledge, the staff realized what they had in Clark -- a 6'4" frame, speed to burn, and decent athleticism -- and decided to fashion him into a speed rusher off of the edge. Brian's recruiting post on Clark acknowledged his athleticism, status as "an Epic Tweener", and was one of few people to mention him as a possibility for the weakside defensive end spot (WDE), which is where he is now. There was a bit of buzz about Clark from insiders, as his athletic ability was apparently quite better than people had thought. He was a project for sure, but people were cautiously optimistic about Clark's ceiling, which appeared to be a bit higher than "average contributor."
The coaching staff decided not to redshirt Clark -- a bit of a surprise -- and he played quite a bit in 2011; he didn't break into the two-deep at defensive end but did come on in pass-rush situations and certain packages. When out there, he showed off his speed and quickness off of the line, but was obviously far from a finished product and made a few notable mistakes in reading the offense (like biting hard on a play-fake that led to an easy Illinois touchdown, for example). He had a good series of practices leading up to the bowl game, and played more in the Sugar Bowl against Virginia Tech than any other game. The most memorable play of Frank Clark's career so far was his interception against the Hokies: Logan Thomas stepped back to pass, saw a receiver in the flat, and tried to lob it to him before Clark came out of nowhere and picked off the ball. That play highlighted Clark's talents and gave everyone some hope that he could develop into a special player down the road.
Clark and Brennan Beyer are the two leading candidates to win the starting spot at WDE this year, and both provide a few unique skills -- Beyer is a little bigger and stronger, but Clark is extremely fast off of the edge. Regardless of who wins the starting spot, I'd expect both of them to play quite a bit, as Michigan's coaching staff loves rotating in fresh players on the defensive line. Both are pretty young -- true sophomores -- but the position as a whole should be above-average. For Clark specifically, look for him to make a few big plays, harass quarterbacks off of the edge, and make strides towards harnessing his speed and becoming a more consistent player.