Those guys are also 38 and 45 years old.
I don't think there is just one type of QB. There have been gymnasts that failed miserably in this league too. Either due to injury or due to once they got figured out they became less effective or in RG3's case he ended up with both.
For me it's having a high IQ. A pocket passer can have success with a high IQ, they can read the defenses and get the ball off quick. If Mahomes didn't have a high IQ with all his tools he wouldn't be the QB he is. He'd still be a starter in the league as he has all the other tools, but he wouldn't be elite.