It is ridiculously difficult to sell a player in this game.
I generally sign Simon Vukcevic in my first season in charge because he's cheap, and has tremendous technicals unmatchable by anyone of a similar price.
Within a couple of seasons I'd have accumulated a title or two, and Vukcevic would have been a good contributor, with 10-20/goals and assists per season. I have some extra money and prestige so I'm looking to trade up to an Aguero or a Pastore, and don't want Vukcevic holding back the development of my younger players.
In the real world such a player would be worth probably £20m-30m quite comfortably. Not in this game though, I can't even get 10m for him. Ridiculous. Everything is based on Current/Potential ability.
And anyone who says that Poulsen, Cole et al. are easy to sell in this game clearly have not played this game. After 2 seasons I finally managed to get rid of them, at a cost of several thousand a week of their wages to myself.