Not sure the latter is true, I don't believe I've seen that in practice. What led you to believe that is the case?
I'm guessing the USTA just makes little effort to calculate full M ratings like they do for C ratings. For the 9.0 team you mention:
- One player played 3 matches, 1 against another self-rate that only played 2 matches. I've seen this occur in Adult league and the player that played 3 matches gets a year-end rating, but it appears in this case the player didn't get an M rating.
- Another played 4 matches, but 2 were against other self-rates that only played 2 matches.
- Another just like the 1st above
- Another played 10 matches including 5 at Nationals and didn't get a rating. Not sure how to explain it, doesn't seem to be an edge case.
- Another played 11 matches including 5 at Nationals and didn't get a rating. Not sure how to explain it either.
Something strange is going on, I'll have to look into it more.