The market value is calculated according to supply and demand within Kickbase. If a player is bought in an above-average number of leagues for a price above his current market value, this also increases his market value. If a player leaves the transfer market without being bought by a manager, this depresses his market value. Players who previously played in the 1st Bundesliga and whose club now plays in the 2nd Bundesliga usually also have a higher market value, because we expect a better performance.