T3’s second zeta not working?

I dunno if this factors in or not but Sith Troopers unique Grant's him a huge defense boost too

Part of the reason GG destroys sith empire is through T3 because he gains crit damage per debuff right? and they're usually smothered in their own stacks of ferocity.

In your screenshot trooper has no ferocity while the others may have had 15 stacks, so you'll get massive differences in damage due to that, irrespective of defense penetration. Just a thought!