This is too bad - if the Yankees were focused on winning, the only way they would be considering not signing Swisher is if they were going to sign Josh Hamilton!
If you think that is an exaggeration, consider the following table. This lists projected 2013 stats for various outfielders; the projections were calculated using the Marcels algorithm. Most of the outfielders listed are free agents; these are the guys marked with asterisks. A few have been mentioned in trade speculation, and Bautista, Markakis, and Joyce are listed to show who's in right for AL East competitors:
In looking at this list, unless the Yankees are planning to sign Hamilton, there is no other free agent worth signing as a regular right-fielder, now that Melky Cabrera is off the board. (Some of these guys - Raul, Ichiro, Hairston - are worth signing for DH/depth.)
If Alex Gordon could be sanely obtained in a trade, as speculated upon in an interesting post on An A-Blog for A-Rod, he would perhaps make sense in terms of making the team a bit younger; however, the Yankees likely would have to give up so much for Gordon that I doubt the team overall would be improved. And even then, you'd be replacing a switch-hitter with a lefty hitter, exacerbating the Yankees' relative weakness against southpaws.
There may be other, less obvious, options for right field that would improve the team. But after surveying the field, signing Swisher seems a no-brainer.
Note: Runs Created (RCs) were calculated using the Stolen Base method.