A team led by Scott Atran returns to Kudilah and provides a first-hand explanation of the will to fight for each combatant. It is not IMHO encouraging and starts with:
An in-depth report on the inconclusive battle to take one little village called Kudilah exposes the weakness of the strategy to retake Mosul, Iraq’s second biggest city... It is April, and fighting is stalled, with part of the Iraqi army forces camped at the village of Kudilah and unable to advance because of fierce resistance and counterattacks by the so-called Islamic State. The research team that first came here in February to talk to fighters on all sides about a ferocious battle that was supposed to be over, or at least ending, is continuing its interviews.

Our aim is to better understand the “will to fight.”
Later he writes at length about ISIS, here is one passage:
Unless we comprehend the devotion unto death among many of the ISIS fighters at Kudilah, like the willingness to die of many of the Paris attackers, we cannot fathom how and why ISIS is also able to expand among myriad rebel groups throughout northern Africa, deepen roots in Central and Southeast Asia, and capture the hearts and minds of countless other European residents who, rightly or wrongly, feel that liberal democracy does not care for them and hurts others with whom they identify.

IIRC Scott Atran has appeared on SWC before.