It has changed from being asst manager to joining backroom staff
Whatever ... there's no reason why DW can't have 2 (or more) assistant managers, maybe a la PS who had Blackley and Summerfield. Perhaps Shirtliff as AM with responsibility for defensive coaching and DB as AM assisting DW with the midfield/strikers with special responsibility for fervour. Not a piss take, as I think Budgie has a lot to offer STFC as part of the management team.