I know almost nothing regarding the LA mob but if the stories regarding Capones alleged influence in the unification of some of the gangs around the Midwest and WC are true, then this might explain all those so-called imports in different families such as Roselli. Afterall Dragna allegedly became the LA representate at the same time or right after Capone became the boss

https://www.maryferrell.org/showDoc.html?docId=95114&relPageId=4&search=capone_detroit