Screwed by the Network: Like Daniel Puder before him, only without the obvious incident to explain what the stick did not like about him. Long story short, he was not the McMahon's choice to win NXT but fan votes carried him to the end despite being booked as a comedic punching bag with the worst win loss record of the rookies as Kaval. After this his loser joke status was taken further and WWE went so far as to mock the fans that voted for him, even after he had left the company since "they had nothing for him."
What Could Have Been: His WWE run as Kaval was a whole mess of what could have been from the minute he won NXT Season 2. First and foremost, the Genesis of McGillicutty was probably going to be the angle that got Kaval (even more) over with the crowd, as he could have dominated them or played a large hand in taking them down. Or at least in theory, but the debut was so botched that the angle was scrapped before it even began. With no story for him, Kaval was functioning as a jobber for three months straight, until he just got fed up with it and asked for his release.
Though if you look at how Daniel Bryan was handled, Kaval might have gotten himself a huge break had he been a bit more patient with WWE management and not expect his big chance to be handed to him on a platter right off the bat.
He was actually fired and was forced to say he asked for his release. Guys who were with him at that time such as MVP (who was released around the same time) came to his defense in interviews and said WWE creative refused to do anything with him or had anything for him and told him to say he asked for it and that he was also at his best behavior at that time. WWE has done similar to Jim Ross, both before and after the Kaval incident.
To be fair, he has in the past screwed himself out of championship opportunities and main event matches due to a noted lack of patience. Even though he was forced out of WWE that was not immediately known to the public.