The boss of the Under-23 side has declared himself culpable for La Roja's early exit and has insisted that the situation must be analysed to see how it can be prevented in future
La Roja last won gold in 1992 and were among the favourites to do so once more, but two shock defeats against Japan and Honduras in their opening games has sent them packing at the group stages.
Spain take on Morocco in their final bracket game on Wednesday, and the coach admitted that their shortcomings must be analysed and learned from ahead of future tournaments.
"I am very disappointed because I think we deserved more. The person responsible is myself," Milla said in a statement on the Spanish Football Federation's official website.
"We need to sit down and analyse everything that happened. Perhaps we lacked something in our preparation, but last year we did the same before the Under-21 European Championship and ended up winning the title.
"The fans will think the coach has been a disaster, that this has been a total failure, and I understand that. But we need to be calm now and analyse what went wrong."