Season 3 I peaked at 3396. I had gotten into playing Rein and was doing great.
The final 3 days I experienced the worst luck I've ever had in the entire time I've played this game. Did I make mistakes, sure - all I can remember is enemy teams with Rein/Zarya/Ana in perfect coordination smashing me every game. I fell to 3015 and, afraid to lose another game, quit for the season.
I've never seen anything like that before or since. I've been Master every season after that