Team Logo. The Frontier Greys were a team in the Frontier League. They were a traveling team, and they did not have a home city or stadium. They folded along with the Rockford Aviators in 2015. Retrieved from "https://prosportsteams.fandom.com/wiki/Frontier_Greys?oldid=14439" Categories: Former FL Teams Add category Cancel Save Community content is available under CC-BY-SA unless otherwise noted.