Couple of things there.
Firstly dropping Duff is exactly what Dingus has previously done, added to that he sent him out on loan.
Secondly, whilst I don't know this for a fact, I would imagine that Duff's expectations in terms of wages are pretty mediocre.
I'd keep Duff at the club. Whilst I wouldn't have him down as a first pick week in week out, are you likely to pick up anyone happy to feature only as a squad player, that is going to be any better