Here's the thing. Remember last year when Darrelle Revis held out? What was the main sticking point of that whole ordeal? He wanted to be the highest paid CB in the league--he literally said he wanted to make "50 cents more" than Nnamdi. He ended up signing for less than that, but unfortunately for us Jets fans his contract was structured in such a way that he's most likely going to end up holding out yet again after this season.
So how does signing Nnamdi Asomugha benefit us, apart from the fact that we'd be acquiring a great player? Well, it's two-fold. First, Asomugha is the only CB that really approaches Revis's level of dominance, so that gives the front office somewhat of an insurance policy in case Revis seriously holds out--for example, if his holdout actually lasts into the regular season. Asomugha would allow Rex Ryan and Mike Pettine to install the '09 and '10 versions of their defense, which as we know is already good enough to be the best in the league.
The second benefit is dependent on the first but is arguably much more important. The cornerback market will be determined by how much money Asomugha takes from whichever team signs him. If the rumored numbers are true and he signs with the 49ers, we could be looking at something like $16 million per year. That will be the number for which Revis is aiming. What we know is that whatever amount he would get from the Jets, it would be a discounted salary. This keeps the cornerback market down--I seriously doubt that any team is going to sign any other cornerback for more money than both Nnamdi Asomugha and Darrelle Revis (thankfully the Raiders don't count!).
So what happens when Revis holds out in 2012? If we don't have Nnamdi, he's got a ton of leverage as we're dependent on his ability to erase the opposing team's best WR from a game on his own. If we do have Nnamdi, that leverage pretty much disappears. He won't be able to ask for as much, and he won't have that single-handed stranglehold on the team's defensive success. It'll cost more to have the both of them, but I think having the two best corners in the league for $24 million a year is worth more than having just the one best corner in the league for possibly $17 million a year.