I have never played a LoL game in my life where the enemy ahead is 4-5 levels ahead

Woooow, that is a difference you can't come back from. Just had a game where the enemy jungler and top laner were ahead of me and my jungler by 4 levels, and ahead of his own ADC by 6 levels (ADC level 9 while top laner level 15)

I think the Dragons might have something to do with this as well as junglers easily falling behind. It's not uncommon for a jungler to be level 4 while laner is level 7. This is quite extreme to be honest.