CHAPEL HILL, N.C. (AP) - Roy Williams always wants his North Carolina teams to run. He knows they can't do that without hitting the glass, snatching down a rebound and kicking the ball out to start the break.
It's why the Hall of Famer has always emphasized rebounding since taking over at UNC a decade ago - and why Williams' Tar Heels have always ranked among the Atlantic Coast Conference's best at crashing the boards. It's one thing this year's group has generally done well even as they've struggled at times after losing four NBA first-round draft picks.
"The simple fact of the game is the quality of my shot against the quality of your shot," Williams said Friday. "And if I rebound it more, some of my shots are going to be close shots. They're going to be tip-ins or follow dunks. That's been the whole reason for me since the day I started."
Since Williams left Kansas to return to his alma mater in 2003, the Tar Heels (11-5, 1-2 ACC) have ranked either first or the second in the league every year in both rebounds per game and rebound margin. In fact, they've led the ACC in both categories in six of Williams' first nine seasons, according to STATS LLC.
Throw in offensive rebounding - the Tar Heels have led the ACC in that for the past four seasons - and North Carolina has led the league in all three categories in each of the past two seasons.
This year's team lacks a true go-to post player such as Sean May and Tyler Hansbrough from Williams' two national-title winners in 2005 and 2009. Nor does it have anyone on the level of Tyler Zeller or John Henson, the frontcourt tandem that helped the Tar Heels to the nation's top rebounding margin last season before becoming first-round picks.
Yet the Tar Heels still lead the league in offensive rebounds (15.7 per game). They're second in total rebounds (43.2) and rebounding margin (plus-6.6) to Maryland, their opponent Saturday.
"If we see one guy in practice not box out, we stop and run every day," Williams said, "because I really do believe it's that important."
Those rebounding numbers impact everything the Tar Heels do, from their ability to get the ball into transition to whether they're playing with any toughness on the interior. It will certainly be a critical factor against the Terrapins (14-3, 2-2), who rank second nationally in rebounding margin at 11 per game.
Maryland, led by 7-foot-1 center Alex Len, hasn't been outrebounded all season.
The Tar Heels were outrebounded in three of their five losses this season, while they barely took an edge on the glass in the other two.
Compare that to last weekend's win at Florida State. On the same court where they lost by 33 a year earlier, North Carolina took a 41-19 rebounding advantage - including 19 offensive rebounds that led to 19 second-chance points in the 77-72 win.
"It's a huge emphasis," freshman point guard Marcus Paige said. "Offensive rebounds are one of the best parts of our offense and obviously we try to control the defensive rebounding as well. ... This year it's more of a collective effort. We don't have (Zeller and Henson) pulling in double-digit rebounds every night, but we have all of our guys committed to try to own the boards."
In a sign of how different this UNC team is from its predecessors, 6-9 sophomore James Michael McAdoo averages a team-high eight rebounds per game, while the next-best rebounders - 6-7 junior Reggie Bullock and 6-5 sophomore P.J. Hairston - are both guards with size.
The Tar Heels have often rotated freshman big men Brice Johnson and Joel James, and sophomore Desmond Hubert alongside McAdoo in search of consistent help inside, though none of the three are playing more than 14 minutes per game. Williams has even gone small with a four-guard lineup for stretches this year.
For now, Williams doesn't care who's pulling down the rebounds - as long as his Tar Heels are the ones hauling them in.
"We work awfully hard to run after (made shots), too," Williams said, "but there's no question it's easier to run off the missed shots so we have to get some of those rebounds."
Also Friday, Williams said junior guard Leslie McDonald is doubtful to return after missing the past two games with a right knee injury. Williams said the reserve hasn't been able to fully practice since tweaking the knee - the same one that sidelined him all last year - last week.