Honestly, I don't think there's a right answer to that question, just a few wrong answers. Ultimately, what is sounds like the group wasn't avoiding is melee getting caught with a cleave as ADS was spinning and changing aggro. But I don't think you can say tanks/melee should always be standing X degrees apart, rather your strategy should account for that possibly happening, and how the group avoids that is up to you. (i.e. 3 seconds heads up on threat change, having melee stand X degrees apart, tanks repositioning slightly when they provoke, etc)
