Most likely they are legit. The problem with matchup mode is that your rank/league points change constantly depending on your activity.
If you don't play the mode weekly, then your rank/points will rapidly decline.
I play the PS4 version of the game and
my scores are way above average,
but I rarely play matchup. If I decide to pay matchup, then my rank is usually at the lowest bronze level.
Each table has some very good scoring opportunities, that can easily boost your score in matchup. Long time players are more likely to know them compared to newer players.