PHOENIX — With the end of the regular season in sight, this is the time when NBA coaches are tested most. That's especially the case for George Karl, who oversees the third-youngest team in the league. "Teaching them professionalism is always a tug of war between coach and player," the Nuggets' coach said Monday. "We're at the time of the season now where players want time for themselves. 'Ah, Coach, we need to rest. We need to relax.'