Horrible Kingpin
And no... I'm not talking about his skin pigmentation. Duncan's physical attributes actually were the best thing about his performance. Only King Kong Bundy would be a better fit in that area.
Duncan's acting is the problem. The acting itself was ok if it was for a random typical mafia header, but not for the Kingpin.
In the comics the Kingpin is a moody and grumpy man that never smiles, but in the movie he's portrayed as suave businessman that smiles and chuckles all the time.