Roy Williams has done the best work of his North Carolina coaching tenure.

Other seasons have been noteworthy, starting with the 2005 and 2009 national championship teams. Even though Carolina was built to win in both seasons, it’s not easy to deliver especially when you’re supposed to win. (Shoutout to John Calipari and the 40-0 Wildcats.)

Before this season, I would have leaned toward the job Williams did in 2005-06. That roster was depleted following the 2005 national title. That team had little experience; Reyshawn Terry and David Noel were the only upperclassmen of note. Williams at times started three freshmen, including Bobby Frasor starting every game at point guard.

Roy Williams has done perhaps his finest coaching job this season. Matt Cashore/USA TODAY Sports

No one knew or expected a freshman named Tyler Hansbrough to lead the team in scoring and rebounding. Williams guided the Heels to a top-10 ranking and a second-place regular-season finish in the ACC.

What Williams has already accomplished this season blows that away. He probably won’t be recognized for it. Virginia’s Tony Bennett will likely collect the ACC Coach of the Year award for leading the Cavs to their first outright title since 1981. But that can’t overshadow what Williams has done. He has adapted more times this season than he ever has.

Williams has mixed in the use of zone defense more this season than he ever has. It’s true that the rule emphasis on allowing freedom of movement made it easier for dribble penetration, so many anti-zone coaches have used it some this season. Early in the season, Williams used a 3-2 drop zone. He saved the 1-3-1 zone he hadn’t used all season until just the right time against Duke to turn the game in the Heels’ favor.

Williams also has been able to win despite noticeable flaws. Carolina ranks near the bottom of Division I in made 3-pointers. Its 62.6 free throw percentage could set a new low in school history.

The biggest reason why I believe it’s his best coaching job is how he adapted without the best player on the roster. Take away Jabari Parker from Duke or Tyler Ennis from Syracuse and it would be hard to imagine the Blue Devils or Orange posting a 5-1 record against ranked teams.

Carolina has been able to make up for the fact that P.J. Hairston is not on this team. Without Hairston on the roster, Williams has had to keep reinventing the Heels during the season.

There was the preseason version that included Hairston and Leslie McDonald being key perimeter players. Williams maintained that he thought their status would be rectified before the regular season started. Because it wasn’t, the first incarnation of the Heels looked like a team bound for the NIT after its loss to Belmont.

Williams had confidence all along that Marcus Paige could become a big scorer. He repeatedly said so last season even while Paige struggled with his shot. Williams moving Paige off the ball and going with Nate Britt at point guard proved genius for two reasons. It allowed Paige to develop a scorer’s mindset that he has carried over even after moving back to point guard. It forced Britt to gain experience he otherwise might not have received.

Nine games in, McDonald’s reinstatement and the decision not to seek it for Hairston brought along the next version of the Heels. This was the messiest part of the season, but without it, the Heels might not be sitting where they are now. Carolina went 4-5 while adjusting to McDonald being back and the changing lineup.

Williams endured a 0-3 start to ACC play without losing the locker room. At its lowest point, he got the team to start believing in defense and playing with a greater sense of urgency. The tweaks he made launched the Heels toward their current win streak.

Carolina hasn’t lost since Williams moved McDonald and Kennedy Meeks into the starting lineup. Their 11-game ACC winning streak is the longest during Williams’ tenure in regular-season conference play. (The 2007-08 team won eight games to close the regular season and three in the league tournament.)

The newest version of the Heels, the one that’s back ranked in the top 20, looks like a team that could make a deep tournament run. And Williams is the main reason why.