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:A 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.
Edit: I guess that with the cap being live, "will play" applies in Bower's case, being his first match of the season.