Adams is not really their back up QB. He's their better QB IMO. Nickson is mobile and shifty, but he's dumb and turns the ball over. Adams is a headier player and more of a passer than Nickson. They've both played a ton and Adams has started his fair share of games.
I also don't agree that UGA is playing up to potential. They looked terrificly mediocre against UT. They weren't able to beat UT by 15 and Ut has been pummeled this year. Yeah they ran up a lot of ydg, but made stupid plays in the redzone all game (and all year really). Vandy has been playing UGA VERY tough the last few years winning in Sanford 2 years ago and taking UGA to the final seconds last year. Vandy's D also leads the SEC in sacks, is 2nd in INTs, and has the fewest penalties. It won't be a huge play for me as UGA has the potential to blow up on someone (See Auburn game last year), but I still like Vandy to lose, but cover the 15pts.