For the Angulimala example, if we read the Jataka, he was a good friend with the Boddhisattas in many past lives. We can also see he had the gati of a killer. The boddhisatta led him to overcome this bad gati. He was also sometimes a yogi who developed jhanas. The capacity of Angulimala to become an Arahant is not by chance. There are others; I forget their names.