I was reading Sando's blog at ESPN, mentioning that counting only games he started, Kaepernick ranks #2 in this season's defense-adjusted QBR ranking, behind only Peyton Manning. That is good the #7 best season since 2008.
How Colin Kaepernick as a starter ranks by other metrics? Where I could, I calculated different stats for the last 7 games of the season, otherwise I used the seasonal value (proprietary stats like QBR, success rate and DVOA). It should be noted that the low number of pass attempts might not qualify him for "official" season stats.
229.7, #18. Low ranked as expected. It, however, represents a 22-yard improvement over Alex Smith (207.4 YPG in 8 full games)
62.50% is enough for the 13th in the league. This is the only stat where Alex Smith is clearly superior (72%).
100.4, #5. Alex Smith, with 104.1 is #3.
8.38, #1. It would have made top-5 in the record-breaking 2011 season.
ANY/A - adjusted net yards/attempt, Pro-football-reference.com
7.50, #2. Peyton Manning is #1 with 7.89. Good for a top-50 season of all time.
AY/A - Air yards/Attempt, Advanced NFL Stats
6.89, #1 in the league. This is the 10th best season in the last 13 years (as far as this stat goes back), with the best ever performance belonging to Peyton Manning in 2004 (7.9).
Success rate, Advanced NFL Stats
48.0%, #14 in the league. Not a pure passing stat, so Kaepernick's rush fumbles and failed scrambles bring it down.
WPA/G Win probability added/game. Advanced NFL Stats
0.227, #6-#7. Includes rushing.
EPA/P, Expected points added/play. Advanced NFL Stats
0.177, #9. Includes rushing.
DVOA, Football Outsiders
25.70%, #3. This is a passing rate stat, which takes sacks and 3rd down conversion rates into account.
DYAR/game, Football Outsiders
79, #5. Surprisingly good aggregate stat. While Kaepernick did not threw 300 yards every game, he played 4 games against good defenses.
Overall, Kaepernick's passing rate numbers (the yards/attempt kind) are elite. As in top-3 Peyton Manning-ELITE, not top-10 Ryan/Romo-"elite". This is his ceiling. Where he (and the playcalling) must improve is obvious. Establish chemistry with receivers not named Crabtree or Walker. Improve in game management skills and checkdown quickly if needed. Turn those 3rd-and-long downs into 3rd-and-short. And, please, none of those boneheaded mistakes.
References and stat definitions can be found at: