Does always seem to give a huge burst of adrenaline in the first one or two games. Can't explain it but it's pretty dramatic.
I think usually it's down to:
- If a manager is sacked it's often because of his tactic, his coaching and more importantly bad relationship with players. New manager means a change in tactic, in coaching, in the lineup and the relationship issue is gone. Other teams have almost no idea what is the new tactic nor the lineup to prepare before the match as well.
- If a manager is sacked the results must have been bad recently. This leads to low morale and bad atmosphere around the club. New manager often gives a boost in morale and somewhat a new hope, a fresh atmosphere.
- Players now have a new chance to prove themself, especially to the new manager.