Complex sentence: But if Stanford can't go to 7th grade, he can't play on the basketball team-as the only 7th grader chosen for the A-team, moving forward means a lot to Stanford.
Split into simpler sentences: But if Stanford can't go to 7th grade, he can't play on the basketball team. He is the only 7th grader chosen for the A-team, moving forward means a lot to Stanford.