@Fyce
Sort of what you said, I just consider a pull having started when the tank moves in to engage and it is usually during that time or after the initial shield lob that I see the regen get cast. After shield lob can sometimes be okay for a single mob, but not for a pack as aoe agro has not been established yet.
@Teryaani
Sadly, I have been seeing this in all the content but yeah ST is probably the worst.