Auston Matthews was charged in Arizona for disorderly conduct. Things included in that category are reckless public behaviour, yelling profanities, public exposure, loitering and public intoxication. Disturbing the peace is what generally falls into those charges, which is what Matthews fell under.
Auston Matthews got lucky and the charges were eventually dropped. He was able to proceed with a great season ahead and never looked back, but unfortunately he wouldn't be the team captain that year. In his career with the Leafs, Matthews has scored 368 goals and 649 points in 562 career NHL games. It's only natural for a player who scored 69 goals in one season, as he did last year, to become a team captain. There's no greater leader than that.