#1 Mohamed Elneny
Elneny is another player on this list who failed to realise his potential. He was signed from FC Basel in January 2016 for around £11 million, but, as indicated by his market value which has dropped to around £9 million, he hasn't lived up to the expectations.
Elneny has featured just four times this season for Arsenal. He's considered by many fans to be a liability, and whenever he's announced in the team sheet, a sense of nihilism wafts over the fanbase.
It would be better for the Gunners to offload him in the summer and put some of that £9-10 million towards a player who could actually be relied upon to do well in his role. There are many hot prospects in European football right now that go for even less than £10 million, so they should search there if Elneny is sold.