CREATE TABLE table_name_98 (league_goals INTEGER, name VARCHAR(255), league_cup_apps VARCHAR(255), fa_cup_goals VARCHAR(255), position VARCHAR(255))
What is the League Goals when the FA Cup Goals are 0, position is mf, League Cup Apps of 0, and name is Ben Thornley?
    
SQL: SELECT AVG(league_goals) FROM table_name_98 WHERE fa_cup_goals = "0" AND position = "mf" AND league_cup_apps = "0" AND name = "ben thornley"