I would think the scouts who brought it to McClay's attention would be first in line. Then, McClay. Then, Marinelli and his coaches.
I really do not know how much weight Marinelli actually has in the evaluation process. I'm sure the scouting department wants to get someone who is a good fit for his scheme, but other than that, I'm not sure he has a button to push that says he wants a specific player. He likely gives his input from speaking and working with a player after that player is under consideration and it is valued to an extent ... but if I'm the guy whose head is on the chopping block, so to speak, concerning draft picks, I'm not going to pick a player strictly based on Marinelli's opinion, especially since Marinelli's never shown that he's particularly good at that aspect of the game.
It's kind of like the Joey Ivie pick that Marinelli gets blasted over. It was a late-rounder when there are a lot of players that teams take a flier on. It wasn't like anyone knew whether he'd turn out to be worthwhile, but Marinelli getting excited about it seems to have made a lot of fans use that as a sign that taking him was Marinelli's fault. I don't see anyone blaming the secondary coaches for us taking Marquez White a round earlier than that or the running back coach for Bo Scarbrough being taken in the seventh round the next year and failing. (Maybe we just blame the coordinators and head coach?)
I tend to blame the scouting department when draft picks fail and give them credit when draft picks succeed, because I really can't say I know the process beyond that.