Question about season end

[jbfg8r]

Do all your players drop a rating level every season when your manager level goes up? So all my 5* players will become 4*?
Does this affect their value? asking because what is the advantage to selling today vs tomorrow. in theory who is a buyer today that will bid up the value? if the value is the same tomorrow, might as well sell then when people are buyers, no? people a level lower will be happy to get your 4* players (which are 5* for them), no?

[Accyrover]

Lose a star and also value. Value maybe 15-20% depending on age and current value. Higher the value more they seem to drop
It's a gamble when to sell, selling today you start a higher price so will maybe make 1m over his value.
Tomorrow, feeding frenzy, may bring twice his value or even more depending on positions and SA.

[jbfg8r]

Boy, have no idea what to do. I'll likely just keep my players. Half of them are 33 and up value and can be 5* again very soon. I can see bidding wars tomorrow and then tokens go too fast. is this a mistake? How much of a team to you typically refresh at seasons end?