Comments from around when he was drafted:
"He played at Notre Dame and embraced coach Jeff Jackson's defense-first system with gusto. He had just six goals as a freshman, but drew plaudits for his defensive game.
"One game I saw him cross the blueline, and just stop," a scout said.
Other scouts said it was difficult to get an accurate read on Sheahan because of the style the Fighting Irish play. One scout referred to Sheahan as the most complete player in this year's draft. Having turned 18 in December, he was one of the youngest players in college hockey.
"He has probably dropped because of his lack of production, but he's learning to play away from the puck," another scout said."
Bob McKenzie: University of Notre Dame forward Riley Sheahan (pronounced Shay-en) had to explain himself at the NHL Scouting Combine for a minor off-ice episode involving underage drinking, but NHL scouts are more interested to find out what his offensive upside is, though that’s not easy to tell when you play in the defence-first system of the Fighting Irish. Sheahan was perceived as a big, skilled point producer in junior before college and scouts are trying to rationalize meager offensive numbers as a CCHA freshman.
June 22, NBC Sports: An exciting prospect before last season, his production dropped off with Notre Dame and he's fallen a bit. Yet he's a gritty two-way player that excells in all areas of the ice, and is more than just a flashy scorer like you see at the top of the draft.
Pretty obvious at this point that he HAS more offensive upside than his college days showed. No one who is picked outside of the top 5-10 is a 'perfect' prospect, but your logic that being picked #21 means he has no more than an offensive upside of 45 points is flawed. Mantha was #20 for example.