it's their histories; your past actions earn your reputations in life....one's currently higher up and better off, the other (whether intentional or not) is currently starting lower and has to work back up.....kind of like averages on exams in a class
That said, no i don't think Manning would be called "choking" in this game if he put up the same stats Brady did, and no he shouldn't be deemed that for his playoff game either
(now if you're upset because you've been having to hear from trolls on the internet...you're going to have to learn that there's no logic (or sometimes intelligence) between them there, and you're essentially always talking to someone repeating something hateful they heard from someone or somewhere else....in about the same way those sea gulls in Finding Nemo incessantly kept just saying "Mine! Mine! Mine!")