Without optimizing for Netherlight Crucicle bonuses (which yellowfive is still working on) that doesn't sound unrealistic.
As long as you are not progressing extremely challenging content severly undergeared (i.e. ToS Mythic under ilvl 900 or something like that) the additional defense gained from defensive relics or higher itemlevel relics is almost completely wasted while Thrash relics provide a significant bonus to our biggest source of damage.
If you're using Luffa Wrappings and/or Incarnation this is even more significant.
Yes, "downgrading" a relic by 40+ itemlevel does feel really bad but that doesn't necessarily mean its wrong.
Of course, this might change depending on which additional bonuses you get in the Netherlight Crucible, but as a guardian druid even most of the tier 2 bonuses are pretty weak...