#4: KAITLYN

This might be more a personal preference, but Kaitlyn could have been in the battle royale at Evolution.
She's fresh in our minds (if you watched the Mae Young Classic) and had a good story that could have been highlighted.
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She's overcome a divorce, a drug addiction and a battle with alcoholism. To be blunt, she had a messy few years in which she needed to find herself.
They could have told the story that she left and came back even better and hungrier. It could have been a story of perseverance and redemption. She, like the Bellas, started her own clothing line.
She's also one of the wrestlers from the Divas' Age that wasn't a barbie doll. She was rough in the beginning, but she turned into a competent wrestler by the end of her first WWE run.
She looked a lot better in the Classic, but maybe they just agreed to a one-off match. Or maybe there's more in store for her. Only time will tell.