What I got from the article was how ISIS are a very different organisation to what many people consider (especially in reference to how they are set up). They need confrontation, because without it their ideology starts to fail and given that this is the main driver of ISIS it needs to be undermined.
A US or Western troop on the ground is the best recruiting tool they can get, however, starve them of a crusader army and suddenly things start to look more difficult. Not so easy to justify the existence without it and war-fatigue will set in. Recent reports have indicated that they have had a number of deserters, there have also been locations which initially welcomed their liberation and quickly fell foul of it.
I saw one report where men were interviewed in a border town in Jordan. The men wanted ISIS to take over, one proclaimed this with a cigarette hanging out of his mouth (I'm presuming he'll be giving that up then - ISIS has a nasty way of kicking the habit for those found smoking). Their main grievances were a lack of jobs and various other annoyances. In short they saw ISIS as a way of escaping day-to-day issues. ISIS would therefore wipe the slate clean for them. Horrifically short term thinking.
Muslims killing Muslims isn't a good rallying call for ISIS, the thinking behind any strategy needs to be denying them western targets on the ground. Empires and Caliphates are easier to beat from the inside (apply stress and watch them implode).
