I think the Islamic State CEO is an unusually stupid terrorist -- precisely because he's turned cruelty into a sort of brand.

For a decade, political scientists have known that terrorist groups suffer when they exercise too little restraint by attacking civilians. Civilian attacks carry substantial downside risks by strengthening the resolve of target countries, eroding their confidence in negotiations, lowering the odds of government concessions, reducing popular support for the group and, all in all, expediting its demise.

Of course there's no denying that a tiny slice of the world's population is lured to Islamic State because of its barbarism. For those itching to decapitate foreigners or cage Kurdish children or rape Yazidi girls, the group's marketing approach is awfully enticing. Simultaneously, however, Islamic State's radical branding has led to attrition; it has encouraged target countries to attack them, spurred desertions from their ranks and eaten away at local support.

It therefore doesn't surprise me at all that Islamic State is losing battles, territory, revenue and the cash to pay its dwindling fighters in its strongholds of Iraq and Syria. Meanwhile, competing Islamist groups, such as Ahrar al-Sham and Jabhat al Nusra, are trading on their more moderate branding strategies to expand their territorial control, membership rosters and material support, especially from Sunni Gulf countries and Turkey.

Other terrorist leaders generally have a better appreciation than does Baghdadi about the costs of extremism; they therefore present themselves as somewhat restrained. When Al Nusra fighters slaughtered 20 Druze villagers last year in northwestern Syria, for example, the leadership publicly announced these wayward killers would stand trial before an Islamic court. When Ahrar al-Sham was accused of mistreating Syrian minorities, its leadership penned an op-ed in the Washington Post, insisting that the group is actually "fighting for justice for the Syrian people."

Indeed, the historical record abounds with militant leaders warning their foot soldiers to refrain from attacking civilians because of the political fallout.