These days, just about anyone can put together an NFL Mock Draft. It just requires that the author have some opinion about who the team in question should take, not necessarily who they will take. Even someone like Todd McShay doesn't really know where all the teams are leaning. But McShay did something interesting with his latest Mock at ESPN. He brought in two NFL Scouts to help him put together his recent mock.
In that first round mock, they gave the Browns LSU cornerback Patrick Peterson. McShay explains the selection.
I've had Peterson projected in that spot recently, but with the Browns ignoring need and taking the best available player one pick before, Amukamara made the most sense to me. The 49ers have bigger needs at quarterback and along the defensive line, but no one available at those positions was worth the pick. Amukamara carries similar value to a few other players at that spot but he does offer an upgrade at a position that is a secondary need.
I agree with McShay in this pick. Cornerback might not be the biggest need, but Peterson might be too good of a prospect to pass up.