#4 His confidence as a character is growing

If you were to ask anyone what Apollo Crews' problem was over the last few years, the answer will always be his character and promo work. He's a phenomenal athlete, but being a great in-ring talent in WWE doesn't mean much when you don't have a strong character.
Bray Wyatt is the perfect example of how a good character always trumps a great wrestler. That's been the department where Crews has needed most work done and from the look of things, that's finally happening as well.
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Perhaps the live reactions to the promos may have hindered his confidence, but he's already become a much better talker in the empty arena shows, further proving that promos have gotten better without an audience.
As long as Crews can have good character progression and get the audience invested in him, then big things are going to come. Winning the United States title could be a part of his growing story arc.