Check the updated S55 News... the Wording was changed to:
we would like to limit the effectiveness of short rosters, used by many teams across BuzzerBeater. We will be looking into tweaks to player stamina effects on late game performance and possibly an age based increased probability of injury for players playing full matches, where older players will be affected more, while draftees won't feel the change at all. We will be testing these changes during the season, and will be seeking your feedback on what the best solution will be.
Now it is much clearer...