You're attempting an outlier with Carter....
Brady
Brees
Rodgers
Manning
You can name a few the last 10 years, the fifth QB often flip flops
You then had Rivers, Romo, Big Ben, Eli Manning/Matt Ryan here and there all battling for this. All of which had at the leagues average for wonderlic at the QB position or well above it (Romo and Eli had 37-39, Rivers is 30)
And I already pointed out to you, there are other factors within the success of a QB - some simply don't have the arm, the athletics, or never got with the right coaching staff. HOWEVER, look at the the list of starting QBs I just provided - each and every one of those QBs have different strengths and weaknesses, yes? Yet, they all held a starting job in this league and many of them have held it for a while now. Almost all of them have either the average wonderlic for a QB or above it. I will state again: Other things can be factored in, however, the best way to determine if a QB can make it in this league is a wonderlic score.
The QBs that often fall out of the average are players with athletic abilities, like Cam Newton. It should be no shock that these players rarely win you a Super Bowl though.