You don't actually need communication to do timers as you can do combat event parsing of when the event actually occurs or do aura tracking of particular buffs.
Originally Posted by Petninja
You would need communication if there was some predefined rotation though but more important than that is in the cooldown of the ability, you can not determine the cooldown of another players ability (you can only approximate by base cooldown). Talents and glyphs alter cooldown durations. A rotation can't be defined in time if you don't know what abilities will be available at a given time.
"In anything, if you want to go from just a beginner to a pro, you need a montage." /w TankSpot WTB Montage for Raiders.