Dyrus won a game in which he was 1/10 recently, in extremely high elo ranked.
I win games while behind all the time, recently won one while more than 14k gold behind, we never actually surpassed them in gold before we ended.
Likewise, I've lost plenty of games due to people doing stupid things. Anything can happen. A player might dc, tilt, a bad fight might happen, you may outscale, or you may even steal an important objective (baron/elder).
That's how I won a ranked game while behind as Kayn top, I snuck into the wall, they missed smite by 78 HP on Elder, My W took it, and we got a massive buff. We used it to end the game and win, while severely behind.
Enemy team was moderately ahead early on in another game, getting dragon left and right, except they always missed smite, and our Jinx always hit rocket. We inevitably won if only because of the massive comeback we were able to do, and how badly we denied them.
Likewise I've had games in which I win lane super hard, and it would be a free game, until our botlaner and midlaner each die 15 and 14 deaths respectively over the course of a match, and they refused to cooperate or communicate, ultimately getting caught out when we were about to make a severe comeback, and instead ensuring our loss. (They walked into the unwarded Jungle after I asked them not too and got instantly killed, for the billionth time, by the enemy Zed).
Those who play this game long enough will be the victor of a thousand matches, and the loser of a thousand more.