In many of those areas that have park and rec districts, they are seperate and independant of the local city govt if it exists. A park and rec district may be in several local govt and cover a fairly wide geographic area. Where no rec and park district exists, we use the schools for fields. However, usually no body wants the job. Tryouts are held every June but no contract is signed.
Players can switch clubs, teams, up down across where ever they want to go.
I have seen coachs hanging about the indoor soccer games to talk with players form other clubs. Many players act a guest players during this time and its just an effort to recruit them for their teams.