I think there's a difference between not being over, and being booked like you're not over. I think Jay Lethal ended up being booked like a guy who wasn't over, but definitely was. If a guy can work, and cut a decent promo, in TNA, he can be a big deal, if those in charge want him to be a big deal. And by big deal, no, I don't mean headlining the show.
The Impact! Zone goes crazy for just about every wrestler on that roster, and Lethal was no exception. Definitely had the most potential among X-Division guys, character-wise. Who else is there? Kaz? He works fine because of Fortune, otherwise, he's as dry as they get. The Gen Me kids are absolutely awful on the mic, and have no character to speak of. Same goes for Amazing Red. I honestly think Jay Lethal was the most interesting character in that group, and had the ring skills to back it up.