Okay I am about done with tanking

[Judge_Xero]

Couple things.

P5 Dread and P5 K/S should not both be alive in P6. One or the other or neither bot not both.
Only leave the bugs up if you killed the T5 Dread. There's too much spike damage to heal when tanking double dread for the OT to effeciently grab all mobs.
If you kill the T5 K/S and don't let the T5 Dread eat any bugs then it's easy to just have the healers stand beside where the T6 Dread drops and have the bugs run and get eaten.

So really there isn't much point in the OT trying to grab the bugs. If you don't want the bugs eaten then have each DD grab a bug/Rook gather them up and mage LB with surecast.

OP, you sound like a competent tank so don't give up. Just be aware of your own limitations and don't let others make you feel like a bad tank for not doing the impossible.
T4:P6 Breakdown - OT trying to gather all mobs

Mobs up - Dread from P5 -- New Mobs - Dread, K/S, 2xBugs, Rook

So, the OT could start in the west, grab the Knight as it falls, which is a free GCD before any of the mobs start moving. Healers stacked in the center so mobs run there. OT runs to the center as the mobs are running. Double Steel Cyclone (probably Berserked) Very solid Enmity in just 2 GCD once mobs become active.

Cons - MT healer will still be constantly heal bombing the MT for P5 Dread so there is risk that they will be hit by spiders and AOE pull-in from S/K causing healing to be interrupted and MT dead. Both healers will be damaged and interrupted. Tank will most likely end up with full Enmity on the Rook, so having to dodge Pox.

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OT Grabbing new S/K. Start in the middle, grab Soldier. Run west Grab Knight. Sit in the West position kiting S/K
Bard South East - Unload on west most bug - use Second Wind etc as required
BLM South East - Unload on center bug - use Manawall - Surecast LB all mobs
Melee - Unload on Rook, stay in position, dodge Pox, use Defensive CD's, wait for Caster LB

So ~2GCD after mobs start moving. Tank has all S/K, healers are in a safe position keeping both tanks alive. 2XBug and Rook are getting LB'd and will be gone soon.

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OT pulling all mobs without using the healers as bait.

Grab center Soldier when it falls. Grab (West) Knight before mobs start moving. Voke Center bug and use Steel Cyclone to catch last bug in SW. Shield Lob SE bug and Infuriate Steel Cyclone again.

So this requires 4 GCD after mobs start moving to secure the mobs. It also requires you to target a mob behind yourself from the opposite end of the arena as well as perfect timing to catch the last bug in your Steel Cyclone AOE. Also, if you healer ends up critting heals, you probably wont be able to pull the last bug with just a Voke + Shield Lob (better hope you have a Scholar as MT healer).

So 4 GCD - high risk - less mobs dead - more OT damage taken.
PROs - Tank Epeen "I got all dem mobs."