Thinking about this, why are we finding it hard to ship out dross? Liverpool manages to sell their dross, for good money too.
One problem is that we are too late in identifying that someone is dross.
The other problem is we are playing the dross repeatedly for the whole world to see that they are dross thereby putting us on backfoot. Liverpool sold Solanke after him much at all. They can always say that "he did not fit their plans". Solanke would then by an unknown quantity that some team is willing to risk buying. On the other hand, we just play these guys every match for everyone to see what they really are. We can't come up with any excuses after that for selling, other than the fact that they are downright crappy players.
We will find it hard because our players are on ridiculous wages. Therefore they can sit out their contract and still play as we have nobody else who can do their job. I.E Mustafi is on around 90,000. He won't get that anywhere else. We have nobody that can come and take his position, so it is in his interest to simply run his contract down, go on a free, and get a signing on bonus that would make up for lower wages.
Mustafi
Xhaka
Özil
Miki
Elneny
Jenkinson
Chambers
Kolasinac
These players are all on wages they will not get anywhere else.