Stupid Question
 

Very simply, why does team spirit fall when acquiring a nasty player, but does not rise when that player leaves or when acquiring a popular player? Shouldn't there be an analogous bonus to team spirit when acquiring a friendly period as opposed to the penalty imposed when acquiring a disruptive player?

Mainly because the TS hit was implemented to discourage excessive trading, not to reflect reality.

What Brillig said.

I've had a TS hit after buying a sympathetic player - it doesn't even have to be a nasty player.

I have a day trader in my series who is scary good at buying low and selling for ridiculously high, but his TS has to be in the pits. If TS wasn't hurt due to excessive trading, this guy could probably afford to field a *good* team after only having it for a month.