Aaron Murray was 6th among quarterbacks by EPA+/pass. Gurley was 13th among running backs in EPA+/rush and 5th in EPA+ rushing. Marshall finished 30th in EPA+/rush. Only Texas A&M, Texas, and Baylor also have two returning running backs in the top 30.
Given this individual efficiency on offense, Georgia's 2.78 points/possession (20th best) seems disappointing. Texas A&M was a full half point/possession better. In addition to raw efficiency, Georgia had the nation's most explosive pass offense and was 15th in explosive plays/rush (opponent adjusted). And the Bulldogs were dynamite on third downs and in the red zone - touchdowns on 76% of red zone possessions. But Georgia ran a play in the red zone on only 27% of possessions, rarely attempted field goals, and didn't have a great success rate when they did. The implication is that Georgia really struggled between the 20 and 40, but I couldn't say why.
Likewise, the defense was a respectable 15th in points/possession and EP3+, but from the outside, the talent was there for a top 10 defense. On the other hand, on a per play basis Georgia was outside the top 20, but they didn't have any major weaknesses offenses could exploit, so the whole was better than the sum of the parts.
Georgia lost talent at wide receiver, but everyone else is back and Murray will still have quality targets to work with. Sans injuries, there's no reason the Bulldogs can't push their way into the top 5 in points/possession. There are plenty of question marks on defense, but there are also potential answers. More important, the schedule is a bruiser. They start the season with Clemson and then play South Carolina and LSU in two of their next three. At this point the SEC East and Georgia's national title hopes could be settled.