Boston assigned Tillman to the G League's Maine Celtics on Monday.
Tillman was assigned to the G League along with Kristaps Porzingis (foot), with both players set to practice with Maine on Monday before rejoining the parent club. Tillman played at least 15 minutes in each of Boston's first four games of the season, but he's appeared in just five of the last 10 contests while logging nine or fewer minutes on each occasion.