Roderick Strong is a solid worker who can work anyone, I think it is funny with his Decade storyline from ROH that he is getting a WWE tryout.
Steen has so much potential, I see him as the next Mick Foley, a guy who may not look like a pro wrestler but can go and bring the fight and bring a compelling deep character with him. He is someone who can connect to a crowd.
ACH is phenomenal, I could see him being the surprising star from the group, he is another guy that like Strong can do it all, just that ACH hasn't had the time to prove himself yet to the national audience. Those of us from Texas who have been watching his battles with Jojo Bravo, Scot Summers, Rachel Summerlyn, and others already know how incredible he is.
Willie Mack could be successful if he trimmed some weight, it would be great to see a guy as big as him doing the moves he does on the big stage though. Who says his move set would get limited? They let Vader and Bigelow do moonsaults, why wouldn't they let Mack?
Michael Elgin, sadly I don't see much in the WWE for him. He is two inches shorter than Ryback or Big E for example and relies a lot on power. Unless Elgin has a whole other side to him that the ROH fans don't get to see then I don't think he is going to go very far in WWE.