From the APA Team Manual page 37
23-Rule. It is permissible for a team to count someone who is on the roster but not present at the match site. In other words, a team may plan on using a SL2 even if the player is not present at the match site. The team would have to forfeit the fifth match, but the advantage they gain is the right to play a higher skill level player earlier in the team match. There is always a chance the player who didn’t show up will arrive later in the match.
When forming a new team, team members should exercise caution regarding the number of highly skilled players they recruit. If the team improves to where it can no longer comply with the 23-Rule, then it must play four players whose combined skill levels do not exceed 19, and forfeit the fifth match. If a team’s skill levels elevate to the point where the skill levels of the lowest four players on the roster exceed 19, then they can play three players to 15. No team will be allowed to add a player to the roster for 23-Rule purposes after the fourth week of play without prior approval from the League Operator.