It can't be a benchmark indeed, but at least we can measure the strength of a team like Leverkusen at this time, whose embarrassing defeat in the pre-season match made many people doubt the Leverkusen team under Ten Hag's coaching and assume that they will not be better in the future, I think it is natural to use this as a benchmark or speculation about what will happen in the future.
I hope Leverkusen management does not regret choosing Ten Hag, given his early performances, even though it was just a pre season match.
Many criticized the decision, but others supported it and gave Ten Hag a chance. However, Ten Hag performance with Leverkusen could determine his future coaching career. He's likely under pressure to improve Leverkusen.