Whether it was giving the youngster a ride to a game in a pinch, coaching his youth basketball teams, or providing constructive criticism, the stepfather was there. And he still is.
These days, Carter-Williams is arguably the face of the 76ers. The rookie point guard shares a luxury apartment with Zegarowski in Bala Cynwyd.
"It worked, as far as the outcome," Williams said. "I'd be a selfish person if I didn't give [Zegarowski] respect for what he's done. And he's done a lot. . . . I just played my position, I'm Daddy.
"Like I always say, it takes a village to raise kids, anyway."
And the NBA's leading rookie-of-the-year candidate has nothing short of a village supporting him.
Living the life
The story of the player known around Philly as MCW starts with his maternal grandfather, who went by the name of Michael Carter. He was a horseman, who at the age of 30 bought 14 acres and built a barn on Cutler Street in 1959.
"His real name is Leroy," Carter-Williams' mother, Mandy Carter-Zegarowski, said of her father. "I think he picked up the name Mike, because white people wouldn't work with him early on over the phone.
"I'm dead serious. He had to say this is Mike and not Leroy, because Leroy was too black."
Once he changed his name to get business, the hardworking Carter found Hamilton to be a profitable place. The town of 7,764 people covers 14.9 square miles and includes pastoral landscapes and historical houses. Hamilton has a feel similar to Devon.
The Myopia Hunt Club holds equestrian events, which include polo on Sunday afternoons. Drivers use extreme caution on secondary roads because they share them with horseback riders.
It's hard to miss the numerous horse farms around town, especially the one Carter owned and which surrounds the two acres where Carter-Williams grew up. (In March, the house was destroyed in a three-alarm fire. It is being rebuilt.)
Carter now resides in a nursing home and is wheelchair-bound because of spinal stenosis. His body fell apart and a doctor told Carter-Zegarowski that her father basically worked himself into being handicapped.
"He never took a day off. Never," she said. "My parents divorced because he was married to his job. He was working with 22 horses. It was the labor that really beat up his body."
Superstar in the making
While he's careful not to destroy his body, Carter-Williams, 22, has inherited his grandfather's work ethic.
The 6-foot-6, 185-pounder routinely sticks around after practice to work on three-point shooting and spin moves to the basket. In addition to his pregame workouts, Carter-Williams often goes over his game performances with Zegarowski back at the apartment.
So far, he hasn't had a lot to be disappointed about.
Carter-Williams led all rookies in scoring (17.2 points per game), assists (7.2), and minutes played (36.2) heading into Saturday's games. The 11th overall pick was second among rookies in rebounding (5.3), and second among all players in the NBA in steals (2.92).
"I said so sort of at the get-go, incrementally: He's better than I thought," Sixers coach Brett Brown said. "He's better than I thought. He's better than I thought I thought."
It didn't take long for Carter-Williams to ascend to the top of the rookie class.
He finished with 22 points, 12 assists, 9 steals, 7 rebounds, and just one turnover in 36 minutes, 11 seconds in the season-opening victory over the Miami Heat. His nine steals were an NBA record for a rookie in his first game.
Carter-Williams was named the NBA Eastern Conference player of the week after the Sixers opened the season with victories over the Miami Heat, Washington Wizards, and Chicago Bulls.
He is just the second rookie to win the honor during the starting week of his NBA career. Shaquille O'Neal did it with the Orlando Magic in 1992.
"I'm not surprised with his success," said Cleveland Cavaliers second-year guard Dion Waiters, a former teammate at Syracuse. "He comes from a basketball family."
Basketball role models
Carter-Williams comes from good basketball stock.
His mother, father, and stepfather all played and coached the game.
Carter-Zegarowski played at Salem State (Mass.). She spent the last 10 seasons as a successful high school basketball coach at Ipswitch High, winning seven Cape Anne League titles.
Earl Williams played at Salem State and was an assistant coach at his alma mater, Cambridge Rindge and Latin School.
The two had Michael while at Salem State in 1991. Carter-Zegarowski met her husband when he was a player at Massachusetts Lowell when Michael was 18 months old. They married in 1996.
Zegarowski later became a respected assistant coach at Charlestown High in Boston.
He is credited with Carter-Williams' maturation into a lottery pick. And his stepson didn't always like going through the process.
The two used to work out at an outdoor court at Miles River Middle School before the family built its backyard court.
"All of a sudden, I would see Michael walking by himself back from the workouts," said Carter-Zegarowski, recalling an episode when her oldest son was 9 years old. "It would get bad sometimes, because Michael didn't always want to fight through it."
But that's just the half of it. Zegarowski would put his stepson on AAU teams with players much older than him, often to the dismay of his wife.
Williams had and still has a different role.
"Psychologically, he helps me out a lot," Carter-Williams said of his father. "He keeps me calm and keeps me patient, always connected with the Lord, and just staying and believing in myself."
Williams never wanted his son to get autographs from NBA players growing up. His reasoning was that Carter-Williams shouldn't be in awe of other basketball players.
"Every time we watch somebody play or we talk about somebody, I always say he's a bum," said Williams, who has another son, Adrian, 13, with his wife, Rosa. "And he's like, 'You think I'm better than everybody.' And I say, 'Yeah.'
"At that time, that guy might have been better than him. But I just knew that he was going to be better than him. I always felt that way."
Carter-Zegarowski's role is that of a caregiver. She always makes sure Michael and her other children, Masey, 16, and twins Marcus and Maxwell, 15, have what they need.
Nowadays, Carter-Zegarowski and her best friend, Tracie Tracy, are running his management team. They are taking a proactive approach to make sure he doesn't spend all his money in a couple of years.
His rookie contract guarantees him $4.5 million over his first two seasons. He could make a total of $10 million if the Sixers pick up the final two seasons of his contract.
But his salary is deposited into a trust he can't touch for three years. Carter-Williams is living off endorsement deals with Nike and Panini trading cards.
That's just one of the benefits of having caring parents.
His mother and stepfather have taught him the value of taking care of the less fortunate.
The couple raised two of Zegarowski's former Charlestown players, James Rodrigues and Anderson Santana. The two are Carter-Williams' best friends and take care of the twins while his mother is in Philadelphia.
"I think everyone plays their role with him well," Williams said. "It's like having an NBA team. . . . If you can't play that role then you are thinking of yourself.
"You are not thinking about that individual: Michael."