Abubakar ShekauFormer Boko Haram leader Abubakar Shekau AP
“You can’t really be more barbaric and more savage ...," Issoufou Yahaya, a political analyst at Niamey University in Niger, told The Wall Street Journal
Yahaya is referring to Abubakar Shekau, the former leader of Boko Haram, the Islamic State's largest subsidiary outside the Middle East.
"He’s the pinnacle of barbarism," Yahaya continued.
After pledging loyalty to ISIS in 2015, Boko Haram, also designated as the "West Africa Province" by ISIS, embarked on a new campaign headed by Shekau. But the extreme violence and tactics of Shekau made even ISIS' leaders express their disappointment. 
Accusing the Muslim "establishment" of corruption and "perverting" Islam, Boko Haram under Shekau had sent children suicide bombers on missions to mosques and crowded markets. Those who refused to join Shekau's cause were considered legitimate targets — including Muslims.
Shekau's strategy didn't go unnoticed by ISIS leaders.
In the August edition of their newspaper, ISIS referred to another Boko Haram commander: Abu Musab al-Barnawia, as the new "governor" of Boko Haram while simultaneously making no mention of Shekau. 
Meanwhile, the displaced Shekau accused his successor of apostasy, and claimed that ISIS head Abu Bakr al-Baghdadi had been deceived. 
Since the alleged split, there have been rumors of deadly skirmishes between the two. One AFPsource claimed that after an attack on Shekau-controlled areas, fighters loyal to al-Barnawia would tell villagers that Shekau's forces had “derailed from the true jihad.”
As far as the effects of the fracturing go, Yaroslav Trofimov of The Wall Street Journal writesthat it could signal a weakening of the organization in the interim. This, in addition to the advances of regional forces supported by European and US advisors, may turn the tide against Boko Haram.
boko haramNigerian soldiers hold up a seized Boko Haram flag after liberating Damasak, Nigeria, March 18, 2015.Reuters/Emmanuel Braun
However, should al-Barnawia manage to absorb Shekau's faction, it could signal a shift of Boko Haram prioritizing their targets from Muslims to the Christians that reside in the region. About 40% of people in Nigeria, Africa's most populated country, identify as Christian, while around 69% of those in neighboring Cameroon, where Boko Haram is also activeidentify as such. 
In an announcement, al-Barnawia claimed his forces would be “booby-trapping and blowing up every church ... and killing all those we find from the citizens of the cross.”
But the difficulty in garnering support for this campaign will be immense. Al-Barnawia's faction would not only have to fight against Nigerian forces aided by coalition advisors, but would either have to battle or recruit those who remain loyal to Shekau. 
“Shekau was in control of territory and of the wealth, Barnawi won’t be able to acquire the resources that Shekau already controls — and the way these guys operate is they always go to where the resources are,” Atta Barkindo, a Nigerian insurgency specialist at the SOAS University of London, explained to The Wall Street Journal.
So far, Barkindo believes that Shekau's forces are the more formidable group, however, this may change if al-Barnawia manages to receive support directly from ISIS. But considering that the self-proclaimed caliphate faces an incoming coalition-led siege, and has been losing territory and crucial sources of revenue in recent months, this may prove to be unfeasible.