Actually the point here is if they are really good then why would their win rate drop below 50%.
No matter how you look at it and on what type of game you are playing those who have below 50% are most likely depend on their team members too,
I mean it is just luck if they would win or not while other players already know it base on their skill .
Cause if you would think about it thoroughly you would know that those who have high winrate are those who also have good skills in the game,
And mostly they are the type of player who doesn't depend too much on their team mates to win they could carry the team to victory.
I disagree that those people who have low win percentage mostly rely on their team. On battle royale there's different modes and it's not easy to maintain a 50% win ratio when you're playing several matches they're not the same as other games where there's only 2 teams. If you check the leaderboards from different battle royales you see most players only have a total of 100 matches on average.
https://fortnitetracker.com/leaderboards/pc/WinRatio?mode=allhttps://pubgtracker.com/leaderboards/pc/WinRatio?mode=1®ion=0