DALLAS — George Karl is tickled with his end of the Allen Iverson-Chauncey Billups swap.

Karl never mentioned Iverson's name Monday morning when he detailed Denver's emergence since the Nov. 3 trade with Detroit. And although Karl initiated a summertime philosophical change to a defense-first system, with Iverson apparently buying in, Karl was clear that Billups has magnified and exemplified his goals, and the team has followed.

"The big thing is professionalism," Karl said. "We weren't a high professional team from the standpoint of leadership off the court, commitment to certain practices, and I think we knew we needed a change of culture or change of commitment."

Did he say practice?

"Things that I've done and the way I've always played the game is something that these guys welcomed, and vice-versa, it's not just one-sided," Billups said. "I appreciate the way these guys play, and the heart and athleticism that these guys have is something that I love."

Rarely does a traded player walk into a new locker room and command the captain's chair, let alone overnight lift a lower-rung playoff team to contender status. Billups is bringing the defense and enjoying the offensive freedom of a looser offensive system.

"He's a tremendous player, but he's also a glue guy," said Mavs coach Rick Carlisle, who coached Billups for one season at Detroit. "He makes other guys better, and he helps instill the team feeling with a group."

Billups, averaging 18.9 points and 7.0 assists, and the Nuggets upended the Mavs for a second time this season Monday night to improve to 17-7 overall and 16-4 with Billups.

Iverson, who skipped a Thanksgiving Day practice, hasn't been as fortuitous with his new club.

"He has a presence that I think is great because basically the simplicity to him is he does the things the right way," Karl said of Billups. "He acts the right way as a professional, he acts the right way as a teammate, he acts the right way as a defensive player, he does things the right way and there's no nonsense."