Here is the way I determine whether a team is carried or is carrying the alliance.
- Compute all team's average score for the event
- For each match, compute the average of Team X's alliance partners mean score across the event. Find the difference between that particular match score, and the new calculated average. Keep track of this number for every team in every match.
- Sum all of the calculated differences for each team together, and divide by the amount of matches they played in.
This should give you a pretty normal distribution of teams centered around 0. If the team is carried, they should get a negative score based on the other teams in the alliance average scores. The team in question's position on the normal curve shows how well they did.. the farther to the right the better. The standard deviation and sample density tell you how hard the event actually was.