There were 17 STARTZs that passed thru Ellis Island and there is a Johann Startz that is from Vakovar/ Vukovar. There is also a Franz who is German and from Vukovar. Franz left in Wukovar his wife Julianna Startz.
The names were not changed at Ellis Island if the manifests were written at the port of departure.The name changing came after the ancestor was already in America. It just might be all in pronounciation, the way an official heard your ancestor say the name Startz/ Starz.