Maybe it was just a bad day. I wouldn't overthink it. Sometimes it just happens, you lose. It happens in the real world - you can do everything in your power to motivate your players etc and have the perfect tactics but sometimes the team just don't show up. Or even more likely your team do an okay job but the City players were just exceptionally fired up for it. Regardless, it is just one game and there's nothing you can do about it.
This x 1000.