New season values

[nothingman]

This is my first season after a long break. I cannot recall what happens after new season kicks off except players quality dropping. Does that make their value decrease as well? If so, I guess it would be good practice sell some players in the last day to make a substantial amount of money. Also, how many hours do we have before all these changes take place? My last match is at almost midnight, do I have enough time to sell out players? I know there are lots of questions. Appreciate any help!