I know so little about soccer that I'm not even sure if that's a joke. I don't think a team can have -6, but I don't know for sure.
I turned over and watched a few minutes of a game yesterday. As I watched for about 5 minutes, both teams appeared to be playing keep away near their own goal and not even trying to move the ball downfield for a score. Maybe they were just waiting for halftime, but the clock counts UP, so I don't know what they were doing. Regardless, it was Boooooooring!
No one understands it.
And now to explain the joke.
You commented that Germany’s dominating second half rally to win 2-1 did not impress you as being dominating.
I then suspected that your understanding of soccer was a passing one, so in order to make my point I employed the well-known device, hyperbole for emphasis.
A negative score in soccer is not possible.