#4 Long-standing frustrations with his booking
You may say that Dean Ambrose has always been one of WWE's top stars for the entirety of his length in the company. This is factually true, but there is a glaring issue with this statement. WWE has always refused to go all the way with him.
He has always been the most misused member of The Shield. Quite a few times, he'd be handpicked as the man to take the fall in Shield matches, to make Reigns and Rollins look strong. And we all remember just how comprehensively he was beaten by Brock Lesnar during their WrestleMania 32 match.
Remember how everyone expected him to branch out and have the spotlight on SmackDown Live immediately after the brand split first happened? He was overshadowed by superstars like AJ Styles and John Cena and subsequently slipped down the ranks.