Just had another look at the cap regulations.
It's the top 25 earners
plus anyone else who has played in a relevant cap game.
Quote will or do playA Club’s “Aggregate Liability” is calculated by adding together the respective Salary Cap Values of the Club’s Players at the given time in question.
A Club’s “Players” are the 25 Players registered with the Club who have the highest Salary Cap Values at the time in question, whether or not they have played for the Club in a Salary Cap Relevant Match in the Salary Cap Year to that date, in addition to all other players at the club who will or do play in a Salary Cap Relevant Match.'"
Not sure what "will or do play" is about.
=#FF0000Edit: I guess that with the cap being live, "will play" applies in Bower's case, being his first match of the season.