It's all a roll of the dice, no matter how "guaranteed" it looks. The other day I was reading "Ask Vic" on Packers.com and he made the point that Shazier reminds him of Zach Brown from the Titans who was drafted in the 2nd round in 2012. He did well his first year and then got benched last year. Here is his profile: http://www.titansonline.com/team/ros...a-4e1d76f9f311
If the Packers are good with Mosely's medical report and he is on the board at #21 and we have him rated higher than Shazier, then go for it. That's why you make a draft board. For all we know, they have Deon Buchannon rated ahead of Dix and Pryor, but figure that most people have him ranked as a second rounder.
I hope we get a slam dunk, Luke Keuechly type of guy, but that's the dream scenario now isn't it?