Don't forget that Georgia Southern was basically relegated to picking up C-level recruits and below; I'd put their overall recruiting somewhere around the MAC. Most major programs simply will not recruit players who aren't a "sure thing", leaving late bloomers and system freaks to the smaller schools.
As far as the A-list receivers and other players go, I see this as being a similar situation to the Denver Broncos. The Broncos have the idea that their system works infinitely better with offensive linemen who are "undersized", by which I mean shorter than 6'4" and lighter than 310 pounds. This means that the linemen they want will be untouched by the late rounds, and they can sit back and stock their roster while filling out the line well after the rest of the "top level" linemen are gone. Tom Nalen was a 7th-round pick, Matt Lepsis was undrafted, Ben Hamilton a 4th-rounder, and so on.
Having receivers that the scouting services regard as "the best" isn't necessary because the priorities are different, just as having "ideal" running backs and "physically flawless" quarterbacks goes out the window as well.