Quite a few experts thought drafting LeRibeus was a reach. I agree, he probably would've been available later. However, I won't rush to say he's not value at that pick. The OLs rated higher than LeRibeus fell because other teams continued to pass on them as well.
The team likely didn't want to take Cousins (or any QB) in the fourth. One could speculate that Russell Wilson being drafted in the third round effected this.
Values & Reaches, 2012 NFL Draft - DraftCountdown.com