APC was founded on a merger of AC and CPC
Tinubu picked Osinbajo as VP
There was never any trust between the two groups and so we never saw the marketed economic competence of the AC/Tinubu caucus
Osinbajo was treated with suspicion and disrespect by those close to Buhari though he acted as president several times impressing Nigerians when he did
The security competence of Buhari never materialised
He made 17 security chief appointments
14 were northern Muslims
Osinbajo was sidelined and Buhari withdrew into an ethnic bubble
There was never any cooperation between both groups
The PDP elements like Saraki,Kwankwaso,Atiku and Ortom were alienated and forced out of APC I
Buhari gave choice jobs to relatives and cronies who were not party members and he made a virtue of not listening.
The same reason he was overthrown in 1985
He truly is the worst president ever

Maybe if there was a better relationship with Tinubu and more collaboration there would have been a better outcome
He never wanted Tinubu to succeed him but showed his incompetence as a politician till the end with his Naira redesign policy

The man knows only tuwo and stew sauce politics and economics.

Buhari failed because he did not carry everyone along.
Even Peter Obi will fail if he refuses to carry everyone along.

All hands MUST be on desk for Nigeria to MOVE forward.