Yeah- good question. It’s not easy to coach 9 year olds to call off the dogs. Hard for them to grasp the concept.
Maybe take a little more time with the ball before getting forward. If you are scoring every 130 seconds, maybe put a time limit on keeping possession. Counting passes can be demoralizing. So maybe run a clock and tell your team they can’t cross the opposing 18 for 5 minutes. Or attack but tell them to shoot the ball wide every time.
Or let the other team take a bunch of corner kicks to work on your defensive shape and counterattacking. If a ball goes out for a throw in- don’t run after it and go forward with your throw. Or all throw ins need to go back inside of your own 18 until you can go forward. Or you can only shoot using your opposite foot. Or you can only shoot a one touch shot.
Or play the secret scorer game- assign 1 kid to be the goal scorer. Your team knows who it is. But the other team does not. Nobody can score but this kid. Put her in as a center back. Watch all of the passing back to get her the ball.
He’s been coaching for a while, so I’m sure he’s been in a similar situation (maybe even on the losing end at some point).