People started to say that AJ is at the tail end of his career, meanwhile Knight just started taking off despite them not being that far apart age wise.
AJ had a history with Cena and Bloodline, but due to circumstances Knight took his spot and his opportunities.
AJ was upset over this and the lack of respect he felt he deserved from Knight
Knight, through circumstances, alsp got in the Elimination Chamber at AJ's expense
All of this frustration is boiling over, as AJ failed to exact revenge on the Bloodline, get into the main event of Mania, or even put down Knight for good, which is turning AJ to the dark side.
Knight is likewise upset that he set out to simply earn his spot and had nothing personal against AJ but AJ took up beef with him and in turn has attacked him and hindered him in his path to a world title in WWE, which AJ has already experienced but he hasn't, and getting revenge on the Bloodline. Both men have similar aspirations so one has to go for the other to succeed, and neither man is willing to step down.
