It is more if we can get our money back I would do that and prioritise giving minutes to somebody like Walta. Some players do adapt and improve, see Vipotnik. Some do not, see Eom, Ronald and Franco. We can not give every player we sign a second season of guaranteed chances in the assumption they will drastically improve. We have lots of squad players already - Cullen, Eom, Ronald, Franco, Inoussa - we need players who improve the starting team and become stars for us like Tymon, Vipotnik and hopefully Stamenic, Galbraith and Walta.
Guehi was a teenager and much more highly rated.