La Roja were dumped out in the first round after defeats to Netherlands and Chile, but Del Bosque suggests that it is difficult to pinpoint the reason for their failure in Brazil.
He told reporters: "We leave with a taste in our mouths of not having met expectations.
"It comes down to a number of things. In the physical, tactical, and coaching aspects, we were inferior to the two rivals we played. It's hard to deduct the one reason since it comes down to a number of reasons. It's been a surprise, a surprise for everybody."