Then again, you could invent a "chemistry" hidden skill, so that the team chemistry is visible, but the impact of adding a new player is unclear. Team chemistry should improve over time, if a group is together for a while, but should not surpass a number influenced by the hidden skills of the team members (probably weighed by the role their are playing in the team).
I´d like to spend some scouting points on existing players btw - to get a "vague" idea about their hidden skill(s). But that´s off topic.
Zwei Dinge sind unendlich, die Dummheit und das All...