There are three ways to reduce imports: (a) reduce spending overall and thereby also reduce spending for imported goods; (b) maintain spending but spend the money on domestically-sourced products instead of imports; or (c) a combination of the two.
My guess is that the reduction of Greece’s imports goes entirely on the account of reduced overall spending due to the depression.
However, let me make an academic argument: suppose Greece’s spending overall had remained stable but the above 13,2 BEUR had been shifted from foreign-sourced to domestically-sourced. Would that not have been quite a stimulus for domestic economic activity and for new employment?
Even in a depression, new jobs can be created. They can be created by stealing them. They can be stolen from those foreign countries which export products to Greece which products Greece could produce just as well domestically.
Quick economic growth is achieved by stealing market share. Greece has to steal market share from those who presently produce products abroad and sell them to Greece. Greece has to steal their market share by producing the very same products on it own and “at home”.