to rate a player.
Usually 9 ball ratings go from 2-12 (in my area anyway).
If the player plays for money, other money players (usually
better ones) will rate them on a scale. Like, Tom is a 5,
and so I will spot him the 7 and the breaks for $100 set.
(I might add that money ratings seem to be the truest
rating, even better than tournament ratings unless they are
the same - The house determines tournament rating. Some
houses will let players in a tournament at a handicap 1 lower
than normal just to fill the tournament up sometimes).
A player would not go down in rating unless he hasn't shot
in over a year, or if he was injured, and thus impaired in his
ability to shoot. Being drunk or drug impaired is not an excuse
for lowering handicaps. That is the player's stupid mistake only.
Lower rated players improve faster and more often than
the highest rated players, and therefore should be adjusted
up in handicap when improved IMO.
Around here, if a player is unknown or new, we usually have
a real good player or two (8 or above) watch them play for a bit,
and rate them as best as possible to start with. If it is obvious
the new guy better than his rating, the TD reserves the right
to raise them up (usually only by 1) during the tournament. If
the new guy wins the tournament, he automatically goes up one.
(Do not have a mediocre player rate people, only players that
are real good, and that can detect faking, and true skill levels.
A real good player (like one that plays for lots of money) can tell
the difference between bar shooters and a player and usually
assign a rating that is pretty true, especially if that new guy has
been shooting on the challenge 9 ball table before the tournament).
I have rated players before, and watched their first match, and if
I think I overrated them, I ask the TD to adjust them down by 1
for the rest of the tournament and thereafter.