Roster moves?

Can someone explain some of the rationale behind roster moves and recalls? Not trades as that would make sense, but more along the lines of moving folks up and down with the Reign. Is it performance based? Salary cap based? Something else?

It seemed guys like Turcotte and Thomas were doing just as good, if not better, than other folks yet they were bumped. Is that just based on a coach/FO decision? Something else?

Legit question here, too. TIA.