At the HEROIC Raid level, what quantifiable standards do you expect from a Healer or Tank to define that they're "doing a good job".
Like, you could have two healers with the same exact gear/party... one would be clearing level 10 keystones, the other having issues with the same dungeon at level 4. What elements can you use to place certain standards ?
Or as a Raidleader/Guildleader, do you look more towards a binary "They are acceptable/unacceptable" when it comes to guild & raid invitations ?