That's because he wants to be comfortable with his role with the club, representatives of the team and player told Miami Herald's Greg Cote, who describes that as a "critical" factor in his decision to play or not.
After returning to the Heat in February following a 46-game sojourn with the Cleveland Cavaliers and playing the previous season with the Chicago Bulls, Wade came off the bench in Miami's last 21 contests. The 12-time All-Star didn't appear to have an issue with that and has said in both Miami and Chicago that he embraced a mentoring role with young players.
Wade turns 37 in January and last averaged over 30 minutes per game in 2015-16. While he's not the "Flash" of old, he showed last season he was still capable of explosive performances - including a 28-points-in-26-minutes outing in Game 2 of the playoffs against the Philadelphia 76ers.