The problem is that if you look at this like the OP has (and seemingly like TNA has at times) you are going to fail. It isn't about finding one guy to change it all around. It never has been for any company. Even Austin took time to get over the way he did, and before that it was a long time for anyone to figure out how to use him. And EVEN THEN, WWE had to go through a puberty phase of sorts and change it's presentation from the ground up.
TNA had the tools around for this. TNA had the time, multiple times actually, to make big changes to the product. TNA had, and still has, talent capable of running with the ball. For whatever reasons, TNA never found the right combo of such things to really make some magic. And whenever they came close, they fucked it all up.
AJ sticks out to me as a guy they could've gone far with. But they screwed that pooch a long time ago.