The 33-year-old returns to London this weekend after a brief stay in his native Ivory Coast following their shattering final defeat to Zambia on penalties last Sunday.
Drogba, who finished joint top scorer with three goals, also failed from the spot in the 2006 shoot-out loss against Egypt.
"It is obviously a major disappointment for him. To what extent personally, I don't know," said Villas-Boas.
"I think there were great prospects for the Ivory Coast to get that trophy for their country.
"It was not possible with the lottery of penalties and, of course, a major disappointment for them for with the dimension of the players that they have."
Chelsea's other Ivory Coast star Salomon Kalou returned on Friday but Drogba was given another two days off.
"It was personal reasons I wouldn't like to share," Villas-Boas said.
Drogba is expected to play in Tuesday's Champions League game at Napoli.
"A player of his quality and so much involved with Chelsea in the past will always help," said Villas-Boas.
"In the month of December, he had an extremely good impact.
"He is a major player for us."
Source: AFP
Source: AFP