The doctrine doesn't mean man is as bad as he could be in every way. It means it affects every aspect of his being including his mind (a tool bent to express his desires), will, and body. This is in contradistinction to the RC/ semi-pelagian view that there is an "island of righteousness" within man. See Sproul's excellent "[Pelagian Captivity of the Church](https://www.ligonier.org/learn/series/willing-to-believe/the-pelagian-captivity-of-the-church)."