The arrival of rookie Norris Cole this season seems to be bringing out the best in Mario Chalmers.Chalmers had 16 points on Sunday in the Heat's 129-90 victory against the Bobcats. Expected to be the team's defensive-oriented half of its point-guard tandem, Chalmers was 4 of 4 from three-point range and improved to 9 of 12 from three-point range on the season."I've just been working all summer on my shot," Chalmers said. "I'm getting some open shots, and I'm comfortable with it, and it's paying off right now." Chalmers had three three-pointers in the first quarter, which helped the Heat build a comfortable lead. His third three dropped with 2:46 left in the first quarter and gave the Heat a 20-point lead."He's been putting in a lot of time and probably this is a residual of all of that," Heat coach Erik Spoelstra said. "It's 10,000 reps and 10,000 hours. Get the reps in and he's been very diligent, and that goes back to the last two years."Forward James Jones, one of the best three-point shooters in the NBA, sees a level of maturity in Chalmers preparation that might not have been there his first two seasons."As a shooter, your strength is in your preparation, and he's prepared himself," Jones said.