I don’t know the specifics about basketball. I know that now men’s basketball and I believe hockey are subject to specific rules outside of the general Ivy rules regrading the AI. Anecdotally, I have heard that one of the drivers of the changes in the rules for basketball was an infamous occasion where Harvard initially announced a recruiting class of six players, one of whom had I believe never started a varsity game but who was an academic stalwart. When rosters were released later that year, this sixth recruit was not listed as a team member. This caused a minor kerfuffle, and now I have been told that the league rules are designed to penalize teams where supported athletes end up not being rostered. But sorry, I do not know the details.