If this is the case, It's like a plaque on Zorn, How long does the Fearful debuff potential on Zorn last? Same as it does on players? If it's a shorter period, then it doesnt matter how close to Zorn you are as long as you attack Toth during this cooldown.? This may make it easier to just switch to Toth for 1 rotation during this period. The only time I have this problem is when the jump occurs directly after the circle phase, because sometimes the safest path out of them is forward.
This is what I do on healer AND ranged DPS....stay 29m from your target, if it is the tank when I am healing i make sure i am closer to the tank than the boss. When the red circle phase comes move forward out of the red circle, as SOON AS the rocks jut up from the ground, return to 29m...rinse and repeat and you will NEVER be out of placement for the jump.