Just as a clarification, the "swing" designation I'm talking about works like this...
Soccer Team has 30 kids that make the grade. So rather than make a JV team of 15 and Varsity team of 15 (making both rather "thin" with injuries and stamina issues. They split the team this way:
10 straight Varsity
10 "swing" players
10 straight JV
The 10 straight Varsity will naturally start most of the games, but there are always some number of "swing" players called up for each Varsity game. And as you might expect, when the Swing players aren't playing Varsity, they are starting JV for sure.
This swing role is great for talented younger players to also get some Varsity experience so they are ready when they mature physically in a year. Rather than just sit the bench on Varsity, they still get play time on JV.
These swing players absolutely earn their letter. Maybe even more than say a Varsity football team of 40 kids where some number sit all year and don't play at all.