Over the past 2 months ISIS has been on a streak of executing their own fighters. Over 200 ISIS fighters have been executed for various infractions from fleeing battle to spying and wanting to return to their home countries. The fact that ISIS is executing their own has to be a downer for recruiting new fighters.
ISIS secret police in Raqqa and Mosul are now monitoring foreign fighters and even storming their homes and forcing them to the front lines. A Kurdish General inn the Peshmerga announced earlier this month that the mayor of Mosul was executed for suspicion of being a spy. It's rumored that Baghdadi attended his execution by way of firing squad. Meanwhile the job of Mosul mayor is not a sought after position seeing as how the coalition killed his replacement already in recent air strikes after just 20 days on the job.