CREATE TABLE table_19398910_4 (class VARCHAR, bout_6 VARCHAR)

when Sanchez ( esp ) w 5-0 were the bout 6, which were the class?
SELECT class FROM table_19398910_4 WHERE bout_6 = "Sanchez ( ESP ) W 5-0"
SELECT "class" FROM "table_19398910_4" WHERE "Sanchez ( ESP ) W 5-0" = "bout_6"