His defence wasn't as good but his reflexes were, perhaps even superior. His chin wasn't up to much though..... even leaving aside the Jackson stoppage.
I think Graham's chin was only bad after he had been knocked out by Jackson, by which time he was an old fighter anyway.Before that it seemed solid enough. Don't think you can compare him to a guy like Whitaker or any other traditional schooled defensive fighter really.He was a largely unschooled defensive fighter(other than his footwork)that relied on natural talent and reflexes.
Graham would have done better had he been with a major promoter. By the time he fought Mike McCallum for the world title he was probably past his best.