I actually drifted away from watching this series regularly when Red John became the centre of the characters' universe and the storyline started to spin out of control. That was the time when he began by invading the offices of the CBI and killing one of his henchmen. Seriously, you are expected to believe that Red John is scotch mist, that he's this untrackable, uncatchable, bogey man that is always going to be impossible to catch, impossible to kill and he's going to keep right on doing what he's doing. And he has all these inexplicably linked henchmen, who conveniently die at just the right time to avoid the CBI getting any further forward with the case. That is part of the reason that the episodes that do not have Red John in them have fallen away in quality and interest. Because how do you top Red John?
Back in the mid nineties there was a series called Profiler, which had pretty much the same premise. A civilian consultant profiler whose husband had been killed by this uncatchable bogey man, and now he's this larger than life figure, committing much the same sort of crazed crimes as Red John. When they finally caught Jack Of All Trades (as he was known), the series kind of collapsed too. I don't know if it was because the lead actress was replaced, but it seemed that without Jack, the writers could no longer function and make a series out of the work of a profiler. Without this monstrous entity, the characters ceased to function. I don't know if that is what is going to happen here, and if it does it would be a shame, because Simon Baker has really made a truly fantastic, interesting character here, and he has the perfect foil in Robin Tunney.
I find Red John's superhuman feats annoying and not in anyway believable, and they just keep getting bigger and more outlandish and unlikely. Having a bogeyman is all very well, but when the bogeyman starts behaving in a way that is not humanly possible, then you have a problem. When he becomes the bound and centre of the universe, then the series starts to lose focus.