My theory is that 'Red John" could be MacCallister, but that MacCallister was not the primary power behind the Blake Association and more importantly Jane's slow burn torture over the years. There has been two clues that were so blatant concerning who is goading Patrick in the viewers face and NOBODY EVER MENTIONS THEM online. I believe it allows The Mentalist writers to write an even deeper plotline that ties everything together longterm while explaining away the nonsensical MacCallister. I believe there is a person who is deeply motivated to out do Patrick.