The Azzurri fell apart in a lapse of 15 minutes at the end of the first half Marco Sau, a double from Danilo Avelar, and Albin Ekdal made them pay.
“There was a moment of blackouts that we paid for dearly,” Sarri told Sky Sport Italia.
“We tried to react to the first goal, but it was difficult to deal with the opposition after we conceded four goal.”
The 55-year-old specialist said that it is hard to tell whether the reason for the defeat is of mental or physical sort.
“Separating the two is very difficult,” Sarri continued.
“It is true that we came out of Monday’s game at Genoa with difficulty, I noticed that during training.
“We had to cling to the game but we did not succeed. Physically, we are not 100 percent.”
Sarri tried not to put any blame on a singular defender for Cagliari’s first goal, which set the tone for the fiasco.
“It would be better if [Elseid] Hysaj had respected the line, because the ball might not have ended up there,” he said.
“We were lined up wrong from the beginning.”