I like the move and it fits the mantra of "transition to a younger core". I was a fan of Santiago and wish him well but you had to deal from a position of depth to fill the black holes on the diamond. Eaton is a left handed hitter, has a high OBP, and should be a defensive upgrade over De Aza in CF.
As a previous poster pointed out, I would have to assume De Aza or Viciedo are being made available via trade. Perhaps they use one of them to try for a catcher upgrade.
The very existence of flamethrowers proves that some time, somewhere, someone said to themselves, "You know, I want to set those people over there on fire, but I'm just not close enough to get the job done." -George Carlin