"It was a tough decision," Spoelstra said. "It wasn't anything that Carlos was doing wrong. He was doing everything that I asked him to do. I think this is what's best for the team right now."
Chalmers earned his second start of the season in the Heat's 120-103 win over Toronto. He had previously started in Arroyo's place on Dec. 15, when Arroyo was in Puerto Rico due to the death of his grandfather.
As a rookie, Chalmers started all 82 games at point guard for the Heat during the 2008-09 season, and 23 games during his sophomore season. He played sparingly at the start of this season, after suffering a high left ankle sprain during summer workouts. He entered the rotation as the team's regular backup point guard just after Thanksgiving. In 38 games, Chalmers is averaging 6.3 points, 2.2 assists and 2.2 rebounds per game with a Player Efficiency Rating of 10.94.
During his tenure with the Heat, the mercurial point guard has shown a flair for the dramatic, sometimes at the expense of more fundamental play. Spoelstra spoke about the challenges of utilizing Chalmers as the team's primary point guard.
"It's been a steady battle and process with [Chalmers]," Spoelstra said. "He has great instincts to make plays defensively. I don't want to completely handcuff him, but he has to do it with an IQ and a discipline to our system. That has to come first."
The Heat play next on Thursday night at Madison Square Garden against the New York Knicks.
Kevin Arnovitz covers the Miami Heat for ESPN.com.