Been lucky to work with several professional football teams in different codes.
AFL teams
NRL teams
Super Rugby teams
National teams.
The number 1 performance killer in every team I've worked with?
It's what I call TWT: the "Team Within a Team" syndrome.
An underperforming AFL team asked me to come in and review things.
Problem: TWT. Half the team were aligned to their star marquee player: the other half were outside of that inner circle and felt isolated.
A failing Super Rugby team asked me to help out.
Problem: TWT. 7 players and the head coach were all sponsored by the one sponsor who only wanted "their" players and the head coach at big events - leaving 3/4 of the player group feeling alienated.
NRL team was going backwards. Asked me for advice.
Problem: TWT. Two player managers controlled the contracts of the majority of the top players, a senior coach and the head of football. They put their own commercial interests ahead of the team's performance.
I will never ever reveal the name of the teams but the message is clear.
Without real team unity you can't win anything.