Both players appear to have been signed as starters, who need to adapt and develop.
With Dibling, it's going to be about getting him game time and rotating into the ACM & RW positions. He'll get time in December, when games come thick and fast and replacing Ndiaye (AFCON).
I think Moyes will have him back on the bench no matter what, when Ndiaye returns.
Rohl is 23 and is a different kettle of fish. On the one hand he seems to add energy, physicality and power to the midfield. He looks set to be unleashed very soon with a view to replacing Gana (AFCON).
I think Moyes may continue with him in the 11 post Gana's return. On the other hand, the major concern I have are his injuries over several years.
My guess is that by the end of the season;
A: Were all seeing he's the Gana replacement
B: He's good but more injuries or a decent offer put him in the sellable category
C: Moyes has him as a bench option.