Peruzzi was due to complete a £3.3m move from Velez Sarsfield to Wearside last week, but a medical highlighted a knee ligament injury he suffered in April and the 21-year-old travelled to Rome to be seen by a specialist.
Velez doctor Ricardo Coppolecchia is amazed at that, branding as "crazy" Sunderland's decision to scrap the move.
"Gino Peruzzi had an injury, it's true, but he is totally recovered and can play," said Coppolecchia. "In the medical tests they will have analysed everything very carefully, and he is in perfect shape. He has even been playing for the Argentine national side.
"We think it is crazy that Sunderland have blocked him. If he returns to Velez, he can play immediately without any problem because he has done the pre-season work. I don't know what happened in England.
"The injury he had wasn't that serious, it could have been talked over.
"The player is in perfect condition and I don't know what is going to happen from now on."