Butt has seen McTominay and Williams follow a similar path to himself when he was coming through at The Cliff.
"Talent gets you through the gate here but what will keep you here is character and commitment," Butt told ESPN.
"With Scott and Brandon, that's just character.
"Character with talent and not talent with character. It's a never-say-die attitude, a will to win. They are both talented footballers, but to get to where they have got is down to their attitude."