Why Buhari appointed Gambari as chief of staff

The newly appointed Chief of Staff to the President (CoS), Prof. Ibrahim Gambari, yesterday declared he was picked for the job because President Muhammadu Buhari needs his competence and loyalty to succeed.
Asked what Nigerians should expect from him as Chief of Staff, Gambari told reporters at the Presidential Villa in Abuja: “We have not started. I’ll have to find out. I don’t report directly to the nation, I report to the president.”
Source: https://guardian.ng/news/why-buhari-appointed-gambari-as-chief-of-staff/