Oh, bubba, his NXT run was the worst. It really goes to show how poor the product was on a weekly basis because they really had four other guys - Gargano, Cole, KOR, and Dunne - cut scathing promos on him, all with solid, valid points, he had zero response, and still won the five way after being barely in the match. He also had a feud with Balor that followed the same pattern.
Now, I know exposing your champ through promos is dumb booking, but the dude had ZERO flavor in the ring. Imagine your description of Randy Orton ("black hole of charisma") was cranked up to eleven. There was no reason for that man to have a year long unbeaten streak.