Star Rating

Can anyone tell me,
I have every player above 22 star rating and most are closer to 30
Yet when I compare my team against another my average star rating is only 17.5
I've come up against teams that have an average of 22-23 but when I check their starting lineup they have players that are only 12-16 stars
Is there something I'm missing?
The average quality of a team take in account all players of the team, including the substitutes.
Exactly. Sometimes I have a starting line up that is much lower than my average just because I am training them up and want them to get game experience. It's a pity I can't set a wanderers team.