Die Mannschaft have won just three of their last eight games and sign off 2020 with their heaviest defeat in 89 as Manchester City forward Ferran Torres scored a hat-trick among goals from Alvaro Morata, Rodri and Mikel Oyarzabal.
“I really don’t know what happened to the team,” Loew told reporters. “We had hardly any chances and we didn’t win a single individual battle out on the pitch.
“In the second half we tried to press them high up the pitch to score and get back into the game but Spain played far better than us, they were much faster and played with more precision.”
Germany needed just a point to secure their spot at the Nations League finals, but would themselves three goals down at half-time and only worsen after the break.
“We walked all over them in every sense,” said Spain midfielder Rodri. “We scored six but it could have been far more. We are still a group with little experience but this will give us a lot of confidence.”