One idea is starving ISIS.
Saudis have reasons better than shale to let prices fall
http://www.freerepublic.com/focus/f-news/3225105/posts
The Saudis haven't increased or decreased oil production.
“Starving ISIS”
Not sure that makes sense.
Most of ISIS wells are in Iraq, and some in Syria.
I will guess that ISIS production costs are reasonably close to Saudi production costs, which are around $10 per barrel.