Personally, By definition Ive always rated players as , and always on a 9'...........
Pro , A player who plays pool for a living. There is a range of skill levels here that encompass both Open and A level players. ( and some Bs

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Open/ "shortstop" , A player who is capable of beating anyone in the world in a race (9/10 rotations, 8 ball, and to a lesser degree 14.1 , one pocket , banks) , knows all the game(s) , Just a real solid player . there is little variances in player skill sets here, and all have their "best/favorite " game.
"A" class, Heres where we can get a bit "loose " with our definitions
To Me, To be an "A" player, one must be a very consitstant and fundamentaly sound player in at least 1 discipline, be it 9/10 ball, straight pool , whatever. But must have this quality . "A"s have wider varying degree in skill sets . Can have an upset against the top players in a short race. sound defensive knowledge, runs racks in small packs . gets out when they should 90% of the time
I dont think location should have an effect on what an "A" player is , just as long as they play 1 game about as well as anyone but the open/shortstops.
NOTE: an "A" class 9 baller can be a "B" class straight pool or one pocket player .
"B" class , again , its about skill sets and consistency, Many are "niche" players , knows enough to get themselves in line or in trouble, they have less consistency then an "A" but can be dangerous at times. Can run rack(s) here and there.
NOTE: A "B" player may have fairly strong offense (A) and weak defense (C), keeping them from beating the true "A" players consistently.
"C" class, Makes some shots, plays a little position , actually tries to play the game . can get out in 8 ball or 9/10 ball once in a while. Has "pet" shots they like to shoot. Weak defense and cant even spell "won pockit"
"D" class, just a banger , cares nothing or very little about position , never saw a shot they didnt like. never plays anything but 8 ball or 9 ball but still enjoys the game.:thumbup:
Im at a point in my game where i feel there is only 2 ways to play, champ or chump.
Tronpocket---------------- (plays somewhere between "D" and "Efren")