4 on the floor

[JetMetFan]

First, there isn't a 10-2-5f. Rule 10-2 only has two articles, unless something was left out of the online rule book.

Second, there's a case book play for this:

10.3.2 SITUATION B:

After a lengthy substitution process involving multiple substitutions for both Team A and Team B, A5 goes to the bench and remains there, mistakenly believing he/she has been replaced. The ball is put in play even though Team A has only four players on the court. Team A is bringing the ball into A's frontcourt when the coach of Team A realizes they have only four players. The coach yells for A5 to return and he/she sprints directly onto the court and catches up with the play.

RULING: No technical foul is charged to A5. A5's return to the court was not deceitful, nor did it provide A5 an unfair positioning advantage on the court.

Part of the logic is A5 is still considered a player because he/she was never removed for a substitute. If you feel A5 was sitting out trying to hide that's something different.