A few weeks ago King Jaja linked to a NYT article reporting that Boko Haram had been substantially suppressed in Maiduguri itself. This attack is reported to have come from outside the city. The attackers descended upon the place in light vehicles. If true, this type of attack is seems fairly typical for areas in or bordering the Sahara; guys pile into HiLuxs, drive some hundreds or dozens of miles and hit a place. They often don't do so well after the initial attack.

Could this be the case in Maiduguri? Boko Haram gets mostly ejected from the city; afterwards they can raid it but can't hold it.