Below are our scoring defense each year since 2008, our national and conference rank, and the last stat is the nation's best scoring defense's average points allowed.
2008: 14.29 ppg (#7 nationally, #2 in the SEC) - 9.0
2009: 11.71 ppg (#2 nationally, #1 in the SEC) - 10.4
2010: 13.54 ppg (#3 nationally, #1 in the SEC) - 12.0
2011: 8.15 ppg (#1 nationally, #1 in the SEC) - 8.15
2012: 10.93 ppg (#1 nationally, #1 in the SEC) - 10.9
2013: 13.9 ppg (#4 nationally, #1 in the SEC) - 12.1
2014: 18.4 ppg (#6 nationally, #3 in the SEC) - 16.0
Two primary observations.
1. The nation's best scoring defense in 2014 allowed close to twice as many as the nation's best scoring defense in 2008 (and 2011, for that matter). An elite scoring defense was holding teams to 10 ppg or so each season. In 2012, the number was slightly higher than normal. But in 2014, no one is holding teams to near 10 ppg. So, it's not just us. Everyone is allowing more ppg.
2. Our relative rank in 2014 was below our typical rank, but we are still in the top tier of defenses in the country. It's been noted that we lacked "star power" on our defense in 2014 and we definitely lacked experience in the secondary. So, it shouldn't be even remotely surprising that our ranks were lower. I mean, it's pretty dang impressive that we had such an inexperienced defense and still finished ranked #6 in the nation.
I still think we're overthinking it. We were young and our backfield was a step down in terms of talent. The general trend in CFB is toward more scoring. Combine these two factors and it would be unreasonable to expect us to be holding opponents to fewer than 14 ppg like we have in the past.