In other words, a one-year deal for anyone is fine, because it only impacts 2013. But, if it's a long-term deal, it has to favor the Mets down the road, otherwise it isn't going to happen.
For instance, the Mets seem willing to bring back RA Dickey for 2013 (his current option), plus two additional years (2014 and 2015). Why? Because RA is awesome and he could still serve them well those two years, plus still have value in trade next summer or next winter with just two years and - say - $20 million left on his contract. However, because it would be much more difficult to trade a 40 year old that has three or four years left on his deal, which is what Dickey wants, they're instead exploring his trade market today.
Honestly, I am growing more and more convinced he will be traded this winter, but it's also I why I wouldn't be totally surprised to see him signed to a two-year extension (if he was willing to accept it). I suppose they could keep him and trade him next summer, though I do think that's the least likely of these three scenarios because it offers the least amount of upside. The only option I don't see happening is signing Dickey to a deal that guarantees him more than two years, for the reasons stated above.