Student or Learner
As principal of a small public high school, Allen took great satisfaction in his girls’ teams. The year before, in fact, the girls’ basketball team at his school had won the state championship. Things looked even better this year: Four of last year’s starters were back again as seniors this year.
(How Good People Make Tough Choices; R. M. Kidder)
Would you be so kind as to explain to me what exactly it means here?
It means that four of the players who usually started the matches (usually the 5 best players make the starting team) came back to school after the summer vacation to begin their last year of high school education (their "senior year" - 12th grade). That means that they are more experienced players; considering that the previous year they had won the state championship, the prospects for the present year's competition couldn't be much better.
Please be aware that I'm neither a native English speaker nor a teacher.