You've got the easiest five keepers I've seen on a team! Solid.
Fielder, Upton, Braun, Rollins, and Wright. They are all in the top three in their positions and all but Rollins still have HUGE upside. Braun will be OF eligible this year too.
If you're going to add anybody, keep an eye on BJ's lil bro Justin this year. And for pitchers, watch out for Ian Kennedy, he could be a solid contributor if the Yanks get off to a hot start.