Where have you seen a skill gradation for opponents??? High, medium, and low!!! There is only the number of games played and the rating of each player!!! When you write about playing against an average player, it would be good to indicate the number of games they have played.... Like, I'll play against an opponent who has played about 20-30 online games.... and even then, it's not a guarantee that their skill level will be average....
But regarding an experienced player - that's perfect, the player's experience is reflected in the current ranking table on the first page of the forum.
Do the words High, medium, and low mean nothing to you? Others understand them, and they communicate perfectly well.
And if you can't distinguish between high and low skill, what's there to talk about?