Celebrity tie-ins are always dicey. Sometimes they work brilliantly, like Shaq on RAW a year or two ago. Sometimes, we get Jenna Morasca teaching us that professional wrestling can always get worse.
You have to have the right guy for the type of business, and Brandon Jacobs seems to be resonating with people. He's a flavor of the month, that's for sure, but he's TNA/IW's flavor of the month. You don't bring in celebrities to build a program for them, you bring them in for the cost-effective ratings bump, hoping to keep those people for later.
This is why I view the various Jersey Shore tie-ins as failures. Where's the audience overlap between the two shows? Who's going to tune in to see (don't ask me their names, I just don't know them), then want to stick around and see more of Robbie E over the next few weeks? Brandon Jacobs is a much different case. Football is America's biggest sport, and he just won The Big One. He's a Winner. TNA/IW is associating themselves with A Winner right now.
Hopefully TNA/IW doesn't overdo this and turn it into a three-month Brandon Jacobs program. You always leave the audience wanting more; send a celebrity out while they're still on top. The idea is to have people going "wow, that was cool!", and not give them a chance to get sick of Brandon Jacobs. If people get sick of a celebrity tie-in, they're going to be more hostile to the next one. Just look at RAW, once the celebrity hosts got to be a bit C-list.
The way it stands now, this is a huge get for TNA/IW. He's not going to be a huge expense, and he might even be one of those guys who's doing it for the thrill. People are excited about him appearing on Impact, which translates to them being excited about Impact. TNA/IW hasn't been able to say that in a while... at least, since Dixie stopped posting so much on Twitter.