1) The performance of all the team members was below standard.
2) The performance of all team members was below standard.
3) All team members' performance was below standard.
In which case:
a) the team-members performed poorly as a group
and which case
b) each member's performance was below standard
I take them all to mean that every individual member of the team performed below standard.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.