SELECT T2.lastname FROM Performance AS T1 JOIN Band AS T2 ON T1.bandmate  =  T2.id WHERE stageposition  =  "back" GROUP BY lastname ORDER BY count(*) DESC LIMIT 1
What is the last name of the musicians who has played back position the most?
SELECT T2.lastname FROM Performance AS T1 JOIN Band AS T2 ON T1.bandmate = T2.id WHERE stageposition = `` back '' GROUP BY lastname ORDER BY count ( * ) DESC LIMIT 1
select t2 . lastname from performance as t1 join band as t2 on t1 . bandmate = t2 . id where stageposition = value group by lastname order by count ( * ) desc limit value
What is the last name of the musicians who has played back position the most ?