Advanced NFL Stats originator, Brian Burke was bought out by ESPN this year. Here is his version of those groupings. He grouped based on similarities to the others in the group so the cutoff lines were less arbitrary. Using two years of data hurts A-A-Ron.
Brian Burke @bburkeESPN 11h11 hours ago
Here's the 4 tiers of 32 starting QBs based on last 2yrs of QBR using a cluster algorithm that min w/in cluster diffs
Wait, so is this list suggesting that Rodgers is a tier two QB, and so is Krappernick?
"The Devine era is actually worse than you remember if you go back and look at it."