If they're not, then they should be.
But a better way of calculating it would be to take the mode. That way a team with mainly 70%+ players and one really low rated player would have an accurate rating. Example;
for the following list of players;
- 82%
82%
81%
80%
80%
79%
78%
78%
77%
76%
76%
75%
75%
75%
74%
71%
71%
70%
69%
69%
68%
68%
67%
66%
65%
65%
62%
48%
42%
Median: = 74%
Mode: = 75%
As you see, the mode gives a far better indication of how good the team actually is. The mean is too easily influenced by extreme values, whereas the mode shows where the rating of most of the players falls.