Player values are set at the start of the season but can vary week by week. In a nutshell this means that if a player performed well his value could increase. If he performed badly his value may decrease. This provides an opportunity to grow the size of your overall team budget by bringing in players who look likely to go on a good run of form. This hasn’t changed my approach to team selection dramatically as by default bringing in form players is exactly what I’d be hoping to achieve anyway. However it may provide some opportunities to grab a bargain.
Values change at the end of a game week, so there is an opportunity to take out a player who has had a bad game week and bring in a player who is likely to rise in price.