The 'success' of the Latvian experience with internal devaluation has come because they, as a country, have no class significant class resistance. Greece does.
Without class resistance, there is no stationary point at which the socially necessary wage will be set. It can keep sinking lower, to whatever level private capital deems necessary to restore profitability on their terms.
1'Bully for the Baltics'- Krugman Blog