Maryland guard Logan Aronhalt, left, protects the ball as he is pressured by Virginia Tech guard Erick Green. Defensive basketball has been the norm thus far in ACC play. (Patrick Semansky/AP)

Coach Roy Williams returned to his alma mater 10 years ago, seeking to restore a struggling North Carolina program to its former glory. Since then, he has seen three national champions come from the ACC — two of them Tar Heel teams — six Final Four appearances by ACC members and 12 coaching changes.

But this season the conference just might be the most balanced since he returned.

“There’s going to be some disparity, because teams like Duke or North Carolina State, so highly ranked nationally, they’re going to win most of their games and somebody’s going to lose those,” Williams said during Monday’s ACC coaches teleconference. “I do think, top to bottom, the league is probably the best in the 10 years I’ve been back. If you take somebody lightly in this league right now, you’re going to lose. I don’t care who you are or who you’re playing.”

Widespread parity has been the hallmark of a conference schedule still in its infancy. Duke, ranked No. 1 in the latest Associated Press top 25 poll, lost to North Carolina State. The Wolfpack fell on a last-second buzzer-beater to Maryland, which mustered just 14 first-half points against Miami. The Hurricanes are unbeaten in ACC play and alone in first place, but nine teams have conference records at .500 or worse.

So what gives? Eight schools have brought in new coaches since the 2009-10 season, causing cultural shifts and growing pains. Perhaps now it’s all coming together, in a year when Georgia Tech had a lead on the Blue Devils at halftime in Durham, N.C., but remains winless through four conference games.

“We went through a stretch there where we were changing coaches,” Williams said. “This year, we only changed one. Once you get a coach who’s been there two or three years, he’s getting his style of play, his prospects and recruits in, I think the stability in the league has been better the last couple of years. That continuity is something to it. The ACC’s never been bad, but the new guys coming in have really done a great job.”

A sizable drop in scoring has coinicided with the conference’s increased balance. Eight teams are averaging less than 63 points per conference game and no team is shooting better than 44.9 percent from the field. Entering its Tuesday home matchup against Boston College, Maryland has become known for slugfests, with halftime margins that read like middling football games. At Miami: 19-14. Against North Carolina State: 22-16. At North Carolina: 42-20.

“You go on down the line,” Maryland Coach Mark Turgeon said. “I think we’re a better team than we were last year. Are we playing well right now? No. But I think we’re a better basketball team. That’s a pretty easy argument to win. Yeah, I do think it’s balanced.”

“I think North Carolina’s pretty good,” he continued. “They weren’t that good earlier in the year, but they were on Saturday. Florida State’s pretty darn good. They struggled early, they’re athletic, gave us some problems. I think Virginia can potentially be better than they were last year. You can go through all the teams, see a lot more consistency. Wake Forest, Georgia Tech, we know are better. I do think it’s a much deeper and better league than it was last year.”

During the 2006-07 season, no team had fewer than five conference losses. That seems to be the most balanced season in recent memory.

As recently as the 2007-08 season, all 12 ACC teams averaged more than 68 points per conference games. The following season, every team averaged more than 67.

This season, in the 26 games since Jan. 5, teams have scored fewer than 60 points 18 times, including Florida State’s 36 points against Virginia on Saturday.

There is no single cause for the trend.

There are few elite scorers in the ACC, and teams such as Virginia and Clemson insist on a grind-it-out philosophy of defense-focused basketball. Turgeon, for instance, preaches a defense-first mind-set, focusing on team principles that often force contested outside shots.

“The parity in the league, it’s early in the conference season, guys are still feeling guys out,” said first-year Virginia Tech Coach James Johnson, who spent five seasons with the Hokies as an assistant coach. “I think the league has been a very good defensive league anyway. I think it’s young. You put a lot of young players out there on the floor, the inconsistency with certain guys, you can see that.

“You’ll see the scores come up a little bit as the season goes on.”