Diaz is a Top 100 prospect. #51 on BA's mid-season list. Waters and Wilson did not make that list. The Braves closest to Diaz in the ranking are Wright at #41 and Gohara at #68.
I'm not surprised to see Machado get this kind of return. We've seem premium rentals like Beltran, Cespedes and Chapman get very strong returns in recent years.
The rental market tends to be all over the place. But the very top guys usually bring back a very good return.
For the guys who aren't at the very top, you can get some bargains. AA should be patient and wait for prices to drop. There are a glut of options in terms of the areas we should be shoring up.
Left side of the infield includes: Moose/Cabrera/Solarte/Beltre/Frazier/Dietrich/Flores
Situational lefty includes: Claudio/Avilan/Loup/Diekman/Duke/Blevins
Some of these guys are not rentals, but will likely be available, which will have the effect of making it even more of a buyer's market.