This is the sixth straight year I've written the QB Index. The initial idea was to track the vaunted quarterback class of 2012, which was headlined at the time by Andrew Luck, Robert Griffin III, Ryan Tannehill, Brandon Weeden, Nick Foles and Russell Wilson. That group has experienced every up and down imaginable over the last six years, from Super Bowls to benchings, from getting cut to suffering career-changing injuries. Luck, Griffin and Tannehill all are embarking on comebacks of various levels of visibility and difficulty this season, while Foles is trying to write a sequel to perhaps the most unlikely playoff run by a quarterback in NFL history.