McAllister
could've been a good or even great Red John if he was properly build up
to be Red John from the beginning.A few things, that would've made him a
better, maybe even good Red John

1. More appearances. Appearing in 1x02
for the first time is a good way to introduce Red John. Give him 2-5
more appearances over the course of the next seasons. Maybe let him
reappear twice in season 2, once in season 3 and 1 or 2 times in season
5.
2. Less dumb first appearance. He was like a buffoon.
There was something creepy about him, but that was not enough. Let him
win at rock-paper-scissors a few times.
3. Give some clues. Noone had
McAllister as a suspect before the list, I personally didn't even
remember him. Don't make him too obvious, but give some clues.
4. Better
reveal. Nothing to say here. NO running away, McAllister was actually
quite cool in 6x03, keep him that way. Don't let him fear death.5.
Longer life span after being revealed. Let him atleast live for about 2
or 3 episodes after his reveal.
5. Show him as the brilliant mastermind
we were searching for 5 seasons. Answer all or most of the questions.And
there you have it: he could've been a good Red John.