Watson and Riley are the only ones that have the potential to be, but I don't think the WWE will get behind them. After Riley beat Ziggler, everyone has been burying him, calling him every name but a jobber really. Even Jericho, who puts guys over, was saying how bad he is kayfabe wise.
Jinder Mahal - Very average, but improving, at least.
Percy Watson - No. He's athletic and can jump, but his ring work is awful. I haven't seen improvement either.
Leo Kruger - Absolutely. Kruger was my favorite in-ring guy in FCW.
Raquel Diaz - Not really. Some good moves. Really sloppy at this stage, but I think she'll be fine in the long run.
Heath Slater - Yes, but he's still more of a bumper than a rounded wrestler.
Justin Gabriel - Probably the #2 guy on this list. He's been really good since returning from injury.
Alex Riley - Will probably never be great in the ring, but he's decent now.
Sofia Cortez - Definitely one of the better in-ring divas prior to her release.
Big E - He's a solid "big man" with above average athleticism for his size.