My daughter (2018) made friends at TG camp with a few girls that played on 2018 black last year. One of them made 2018 black again and requested to be moved to purple. Her stated reasoning was because she's not one of the coach's favorites. Another reason might be because she will have more opportunity to "stand out" on purple.

For 2018, I was told that five girls moved from black to purple and visa versa.