The OP appears to be a decent player who mostly plays match play, It appears that many of his matches are against players with an average higher than his, Then if they beat him they have to be a "house player" with more than one account,
He has to accept the fact that some players play much better than their average when they play match play. Or their average shot way up when they first tiered up and though their average is still higher than his it is on the way down,