I'm confident that our young guns (Sloan, Amone, and Sullivan) will get plenty of game time in 2021. Questions about where Sims, Bird Mbye fit in will be a subject of interest all season. For me:
Sims has to find better form than what he displayed late last season. If he can, the back 3 should be Sims, Su'A, and De Belin.
Jack Bird is another matter. His fate may solely depend on the available vacancies in the team (injury or Bad Form).
I see Mbye as a backup player for the halves and fullback, that is, Sullivan, Amone, and Sloan. These players are all young guns who may need to be replaced from time to time next season to give their bodies a rest from the riggers of first grade.