Another downside to continually signing big free agents is that you don't ever have a down year where you get higher draft picks.
I doubt the Sox ever have a fire sale under DD like we did with the AGon/Crawford/Beckett deal or the Lester/Lackey/Peavy/Miller/Doubront sell off. You have to have a losing season to make that choice.
The Yanks made a very strategic choice to deal some talent, and they maximized the return for the most part.
They may not have signed as many big ticket FAs as the Sox recently, but the Stanton trade was like a big signing.
The one thing the Yankees rebuilding effort does show is that it is possible to stay somewhat competitive while you rebuild, and that it takes some serious risk-taking to make it happen.
I'm not sure, if DD would ever have the balls to trade off top talent, even during a down year. It seems like a problem we have, and it's hard to view winning as a problem, is that we may not reach a sell-off period until 2020. By then, many of our big return players will be gone or re-upped at massive contractual costs and won't be tradable/