It´s not a matter of high or low, but rather what are you getting from a player in a particular range. We should break this down into brackets really…
0-500 rating - You know you can expect 2 of the 3 dps to only have 1 ability used the entire run of the dung, unless they’re a hunter. then they will have just pet damage.
500-1000 - You can expect the tank will get knockback on the dragons in grim batol and fly off the edge to imminent death.
1000-1500 - You can expect your melee dps to have used their interupt at least 6 times throughout the run. Your healer might occasionally ask for a mana break, but you know if there is a death they will get the bres off within 30 seconds. Sometimes your mage will lose to dodgeball but your other 4 members are good enough to overcome the last 67% of the boss without them.
1500-2000 - You can some expect weak auras and mods installed and decent class knowledge as well as some knowledge of the fights, but not all. You might get that clicker heals but they’ve been playing like that since cata so you will probably be fine. You know the shaman will use bloodlust when it should be and at least 3 of the party members will be fully consumed.
2000 and up - Congrats because you made it. Pugs all over azeroth know 1 of two things about you. Either A) They are a good and experienced player and would be confurtable taking you in the group. OR B) This crazy sob just sat through grinding that rating through all the rubbish above and they know at the very least if ish goes south, you have the patience to stay and wont bail on the group mid run.
If you clear all 8 dungeons at keystone level +7 that’s a score of 2,120. Achieving that early in the season just means you’re ahead of the curve and achieving it towards the end of the season probably means you’re behind the curve. That assumes the Base Score for a Key on RIO’s FAQ is up to date for TWW Season 1.
I don’t know exactly how the color-coding of a score is applied by Raider IO, but the All Run Leaderboard shows the top 3 in gold, 4-10 in orange, 11-100 in purple, 101-10,000 in blue, and 10,000+ in green (or white for really low ranks). The top-ranked player #1 in the world has a score around 2,817, while the highest ranked “green” player at #10,001 has a score around 2,300-2,350 at the time I write this.
IO is just for matching to other people near your score, it’s not bad or good. Certain players forming groups could be considered bad when they require a score that is significantly above what the keystone-level requires on average for success (I guess that would be labeled “gate-keeping” by those that hate scoring systems).
It’s really not that big of an achievement this season. There’s no split rating to farm for free elo, you only need 7s, and this week’s tyrannical is easier than fortified in current season.