Unfair Tactic (or not?)

[Theisey]

An NCAA team I'm familar does something very close to this
and we feel that this is not using the substitution process
and therefore is legal even if team B fails to reacts.

They in fact did this twice in the game. The defense covered
the player on the first attempt. Team A calls TO to change play.
The second time, team B did not cover and the play ended with a Team A score.