So you agree, the Yankees have an advantage. Thanks, that's my point.
Can't keep up? I think the Sox have kept up very well. Nobody's saying they can't keep up. They just aren't going to sell 6 years worth of all-star caliber production for half a season of all-star production. Additionally, they're always going to be hesitant to sell that potential 6 years for a half-season, even if there's no assurance that the 6 years will materialize. Lester, Buchholz, Papelbon, Pedroia, Youkilis are all examples of that decision paying off. Many would have traded Lester for Santana a few years ago. The Sox didn't and it was the right move.
Yet, other teams wouldn't offer a cost controlled player who could be worth $15m/yr ($90m over the course of his 6 years) for half a season of an all-star. It is a financial decision, actually. The $$ involved isn't a deal breaker for a lot of teams, but to pretend that it isn't part of the equation is silly.
I acknowledge that the Yankees have the piece the M's want, and I'm not jealous of the Yanks acquisition of Lee. I'm just saying that the reason other teams hold onto prospects IS NOT BECAUSE THEIR PROSPECTS AREN'T GOOD ENOUGH to be traded. It is because prospects who develop into good players are more valuable financially than expensive SPs and all-star hitters who are about to be FAs. This explains why the Yankees have held onto Phil Hughes. He's very good and he's essentially free.
That savings doesn't just sit on the books for teams like the Sox, Yankees, Phils, Dodgers, etc., it gets reinvested in the system, or into other FAs who become key parts of the team.