Rogue burst can outrace a single Warrior's sustained pressure - pre-shield on cooldown and Penance the instant the opener lands so the Warrior never falls out of Mortal Strike range.
Kite/CC chains buy the Mage and Rogue time to burst the Priest - Warrior should peel off the healer with Piercing Howl/Hamstring the moment the Priest is trained.
Two Rogues can burst either target near-instantly - keep PW:S pre-cast on the Warrior and be ready to trinket the second stun, not the first.
Both sides shield and Mortal Strike through the same plan - it comes down to who lands a stun during the other Priest's Penance cooldown.