I think that's one way to look at things, but common opponents and scores of games differ vastly due to factors as well. Did they play at home? Were they penalized more? Did they have more turnovers? There's flaws to each and every system and way of looking at match-ups and attempting to predict trends.
You're kinda saying that stats don't matter at all here, considering that input then no team is better than any other team ever. Stats can help paint a picture, but the game still has to be played so there is margin for differences.
If you guys want just a broken down scoresheet of points vs points of common opponents it's pretty easy to find that, look at the schedules of both teams.
Georgia outscored common opponents - 168-60
Bama outscored common opponents - 134-75
If you just for some reason look at just that stat line, Georgia probably should be favored by 10 points or more in this game. We have no hope, the sky is falling, season is over. Didn't realize you two were so pessimistic about our chances