I wonder how and why he was convinced to play that role, They probably told him that was the only way he was getting an Oscar.
His Oscar is for playing a corrupt hood cop
I know he got an supporting Oscar for this:
But damnit he killed Matthew Broaderick in this and he was no slouch.
But that brings up another point when he did get a gong it was when he played against type i.e a Slave and a corrupt cop.