Colorado's dynamic 6-foot-7 forward has obviously picked up where he left off as a freshman when he led the team on the boards.
But during Thursday night's 67-58 loss to Wichita State in the Puerto Rico Tip-off, the old problem that haunted Jeff Bzdelik's Buffs before Tad Boyle and Roberson arrived on campus cropped up again.
CU was out-rebounded 38-24 by the Shockers and outscored 13-2 in second-chance points.
"We had some breakdowns in boxing out," Boyle noted. "Sometimes (Wichita State's) best offense is offensive rebounds. So we knew boxing out and help-defense were going to key and we broke down a few times help-side."
The Shockers had 11 offensive rebounds in the game. Garrett Stutz, a 7-footer, grabbed five of them and finished with 14 points and 11 rebounds.
"We realized that we pride ourselves on rebounding and we worked on that and our offense just went with it," Stutz said of Wichita State winning the battle of the boards 24-14 after halftime.
Ben Mills (7-0) and Trey Eckloff (6-11) were the only players on the trip that did not see any action. Sophomore wing Jeremy Adams (concussion) and freshman forward Damiene Cain (recently rejoined the program), two players who could help the rebounding situation later in the season, did not make the trip.
Carlon Brown and Austin Dufault were CU's second-leading rebounders for the game with four each.
"I just feel like we need to lock down more on defense and get stops," Roberson said.
CU will play Maryland in the consolation bracket today at Coliseo de Puerto Rico (7:30 p.m., no television). The Terrapins were out-rebounded 47-29 during a 62-42 loss to No. 15 Alabama in the opening round.
"Our rebounding wasn't that great," first-year Maryland head coach Mark Turgeon said. "But we tried hard."
On the other side of the bracket, Purdue improved to 3-0 with a 91-90 victory over Iona and Temple handled Western Michigan 69-55.
Robbie Hummel made the decisive 3-pointer with 20 seconds left and finished with 24 points and nine rebounds to lead the Boilermakers.
"I thought Hummel was the man tonight," Iona head coach Tim Cluess said. "We got overly sloppy at some moments of the game. That's on me because I didn't do a good enough job apparently."
Temple handled Western Michigan 69-55 in the opening round with all five Owls starters scoring in double figures.
"They came out and punched us in the mouth right away. They played a much better game and came out more confident," Western Michigan head coach Steve Hawkins said. "We need to get our swagger and that's why we're in this tournament."
Purdue plays Temple in one semifinal. Iona and Western Michigan will meet in the consolation bracket.
Doing the Charleston
CU will participate in the 2012 Charleston Classic next season. Other teams in the field include the host College of Charleston, Auburn, Baylor, Boston College, Dayton, St. John's and Southern Illinois.
This year's Charleston Classic, being contested this week with the same format as the Puerto Rico Tip-off, includes Georgia Tech, LSU, Northwestern, Saint Joseph's, Seton Hall, Tulsa, VCU and Western Kentucky.
The Buffs competed in Rainbow Classic in Honolulu in 2008, the Maui Invitational in 2009 and the Las Vegas Classic last season. CU's combined record in the events was 3-5.
Wichita State now leads the series with CU 6-3. ... The Buffs will face Maryland for the first time ever and are 4-4 all-time against ACC opponents. ... This is CU's second trip to San Juan and last made the trip in November 1998. The Buffs lost to Kentucky (64-52) and Xavier (74-61), and defeated American-Puerto Rico (101-56).