What is the reason that makes some matches end up one sided, even in pro gameplay i see that happen sometimes. I am pretty sure it is not(but maybe sometimes in solo q or comp in general) because of mechanics. But what is the reason behind...

I just played a game that had our Omen disconnect in the first round. We tried to remake but nothing worked, even though the remake conditions were met. We played the rest of the game 4v5. What gives?