I think both of these players had a great love for the game and extremely high standards that they set for themselves. They played so much that they got to the point where they could look around at a tournament and know that no matter what happens to them, no matter how many bad breaks they get, they'll hit enough good shots during a tournament that they'll either win this week or, if not this week, next week. This has a huge impact on a person's confidence.
Every serious player has had that experience of practicing for a tournament and not missing a shot for weeks and then on the day not being able to perform. They leave the course despondent and think maybe they just don't have it. I think Hogan went through the same experience but he had the drive to keep going until practice form and playing form were more closely correlated. Hogan hit it so good while practicing and practiced so long and so well and then entered enough tournaments to eventually get to the point where he knew he could hit it great under pressure. He was able to work out what it was that changed from practice days to tournament pressure and adapt, feel more comfortable, and eventually get that inner cockiness where eventually he could enjoy the intensity of major tournaments. He knew they didn't have the control over the ball he had. Not over the course of 72 holes anyway.
That's my take on it for what it's worth.