https://www.warcraftlogs.com/reports...&view=timeline Take a look at this timeline, this is the highest dps unholy parse on shriekwing.
He dumps his CDS at the beggining with his opener which are all just fire and forget guardians, and then he basically presses 3 buttons and just presses his CDS on cooldown as the fight allows. Something like 70%ish of the damage is coming from those guardian CD's.
Its odd to pretend like the spec is anything other than what it is. You dump guardian CD's and then you press 3 buttons for a loong time to reduce the CD of said guardian CDs so you can dump them again. That's the entire spec.