Speaking at his post-match press conference, Koeman said: "I can list quite a few mistakes. We started very badly. We did not defend well. We were not aggressive, there was a lack of pressure and we lost the ball as well, particularly at the start so it was really very bad.
"The players ran a lot, but not in the positions so it was awful, very bad. We did not control the match. The match against France was reasonable as a team, but today it was appalling."
The 61-year-old, who has a contract valid until the 2026 World Cup, added on the speculation over his position: "It is not a question that should be addressed now because I don't like to speak about these kinds of questions: what happens if.
"If it happens I will try to have a response. I am responsible for this match, but we are still in the next stage and have to play much better. It is possible with this squad. They have the qualities. If we fail, you can ask me this question [about my future] again."