The Taliban's smooth and rapid transition after their acknowledgment of Mullah Omar's death sends a strong message: They are afraid of the potential rise of the Islamic State militant group in Afghanistan if they fail to project unity. That reality should be useful to the U.S. government as it tries to negotiate a transition deal with the Afghan government and the Taliban. It's still true that the Taliban can demand something close to de facto control as part of the deal. But now, the Taliban have an incentive to talk that didn't exist before the rise of Islamic State. They have something to lose if the country devolves into congeries of competing warlord-controlled territories.

The man who will replace Omar, Mullah Akhtar Mohammad Mansoor, was Omar's deputy and has been effectively leading the Taliban since Omar's death, and perhaps before that. His selection seems to suggest that the Haqqani Network, a faction that has gradually become powerful enough to rival the Quetta Shura within the Taliban, was willing to compromise on leadership, rather than pressing for Omar's son, whom the Haqqanis were rumored to favor.

The two deputies to Mansoor, however, are one of the leaders of the Haqqani Network and a former Taliban judge who is said to be close to the Haqqanis. That signals a kind of grand compromise between the Quetta Shura and the Haqqanis, who've struggled for dominance over the years.