When the first season of the National Women’s Soccer League kicked off in 2013, only one of the league’s eight founding teams — the Portland Thorns — was affiliated with a men’s soccer team. The rest entered as “independents,” a designation that now represents only one-third of NWSL teams heading into the 2019 season. At the beginning of 2017, the Western New York Flash were sold and moved to North Carolina, where they are now affiliated with a USL side.…