There are two ways in which a player is valued. One is the Market Value which is set by the Worldwide Transfer Market and the Salary paid by the team.
Always keep an eye on a player's Salary and Market Value by selecting [My Team], then [Squad List].
Players who have great Affection for the club will happily play on a low Salary, while the opposite is true for those with little Affection.
A player being paid a Salary well below the Market Value can become very unhappy and turning down wage demands during Contract Renewal can lead to a player losing his Affection for the club. Make sure to pay your players an amount which is a fair reflection of their contributions