Database: professional_basketball
Question: How many turnovers per game did the assist champion had in the 2003 NBA season?
SQL: SELECT AVG(T2.turnovers) FROM players AS T1 INNER JOIN players_teams AS T2 ON T1.playerID = T2.playerID WHERE T2.year = 2003 GROUP BY T1.playerID, T2.assists ORDER BY T2.assists DESC LIMIT 1