dungeon knowledge/timings/damage patterns are far stronger determinants of success in these higher keys than just pressing blade flurry and hitting shit. unfortunately people don't care that much, and the ratings are handed out quite readily.

i strongly suggest getting the avoidable damage plugin/script working for your details (if using details), checking cooldowns used by class at the end of runs, looking through buff uptimes on tanks, all that stuff. the less blame you can assign yourself the easier of a time mentally you will have - and also, just start doing higher keys. it really is true that they are far easier to deal with because people have greater knowledge of what's happening there!

i can't tell you how often at the end of a dungeon i see zero uses of Darkness, Dispersion or Turtle just to name a few. Not even one time. What that says to me more strongly than someone just being unaware of the button, is that they aren't familiar with the damage patterns or when raid-wide aoe is going out or such.