Well, I don't think anyone right now can increase TNA's ratings. Not in WWE, not on the indies, not in Japan, nowhere. The same goes for the WWE. No one in the WWE draws ratings. You may argue that Cena does and that MAY be true, but I doubt it. We've seen RAW with and without him, him as Champion and as a backdrop, and there's no change. The most logical conclusion is that he's not a ratings draw. He draws merch and live audiences, but ratings - I don't think so.
Actually, I really think wrestling is at an age where a single wrestler cannot draw ratings. The whole thing is a misconception. Whenever TNA signs someone people immediately say "he won't improve the ratings". The same thing is said about every small change TNA does. Six-sided ring, four major PPVs a year, going on the road, going live. The truth is, none of those things will improve the ratings individually.
What I believe can improve the ratings is a great two hour wrestling show. A show that looks good, flows well, has interesting characters played by talented wrestlers, interesting stories (not innovative - interesting), and a nice crowd to make some noise. Hence, the WHOLE product has to draw ratings, not just one or two or even three major superstars. Once you have that, you go out and you market the hell out of it in any way you can. Then you just hope your show is good enough and people stick around. It's difficult as FUCK and if there was a way to have just one dude come on and bump up the ratings I'm pretty sure the entire genre wouldn't be down the crapper right now.
That's why when TNA signs a new guy we shouldn't say "how can HE improve the ratings" but instead wonder how can he fit into the entire show, and what can he deliver in order to make it A LITTLE BIT more enjoyable for us. Once you have people like that, you add more and more, you drop some, you get new ones, and since they all contribute to the show A LITTLE BIT, in the end you have a wholesome roster capable of telling great stories, wrestling any kind of match and complementing good writing from capable writers and bookers.
People talk a lot of smack about the Attitude Era and how it relied on third grader humor and shock value, didn't take care of the wrestlers' health and it was too obscene. While I don't agree that those things are bad, I understand where those people are coming from. However, nobody can deny that these shows had this wholesomeness I mentioned. There were so many fun guys around. You didn't look forward just to the Main Event, there was entertainment to be found everywhere. Mid-card, low-card, jobbers, segments, main eventers, tag division, even the damn women's division was watchable. Jericho alone didn't draw ratings for them, neither did Funaki and Taka Michonoku. I suppose the only people who actually drew ratings were Rock and Austin, but the entire product would've stunk if it was all Rock and Austin who were good. Rock and Austin were AMAZING, everyone else was either good or great. Very few rotten apples. So - you have yourself a well balanced product that you can enjoy for two hours, because all the guys involved were talented and played their parts well regardless of where they were on the card. That's why it was so easy to transition people like Y2J, Eddie Guerrero and Edge into the Main Event, considering that they were wrestling, talking and performing like main eventers when they were just in the tag division or having a random feud with Kurt Angle.
With all that being said, CM Punk is a guy that can add quality to the show as he is one of "those" wrestlers. He won't save TNA on his own, he won't draw ratings on his own, he needs all the help he can get and so does everyone else. I think that's been TNA's mentality recently and if that's the case then we're in luck since that puts our benefit first.