Vaughn isn't getting dealt.
Burger was an early first rounder, is known to have a great hit tool, and Lord knows you can't question his heart. He's certainly trade bait but I think we would have to be overwhelmed to deal him this season. While there's no obvious position for him to play, be it now or in the near future, I think we'd be selling very low on him right now (AAA stint excluded).
Sheets could grow into the piece we've needed since Jim Thome left, a power hitting LH bat. I like that he's apparently getting coached up by his dad and Cal Ripken, makes contact, and seems to have a decent eye. He could grow into a player but in a deal for a true impact player (not a rental), he's trade bait. I'd hesitate dealing him for a 3 month rental.
Mercedes. No one will want him.