To be fair thought, he hasn’t been able to take advantage of the opportunities given him. He’s had every chance to supplant Singletary but he just hasn’t been able to.
That could be scheme and coaching problem, or it could be talent. Probably a mix of both.
Moss had an excellent early season. I would argue that he was RB1 caliber for a short period of time. McDermott swapped between Singletary and Moss every offensive series. He has had plenty of touches. That said, Buffalo uses its running backs in a particular manner under Josh Allen, and that manner may not best suit Moss’ set of skills.