all you have to do is create them before starting your franchise.
just try to forecast who will be the good rookies in the next 10 years.
get their ratings or create any player (with any name) with the same game as them.
then all you have to do is edit your created players' birthdays, names, and years pro (you can do this in console versions!) at the start of the season and walla! you have a rookie eligible to become the year's rookie of the game.
in the consoles, you cant edit the ratings in franchise, so its important to create players WITH THE SAME GAME as your forecasted rookies. when its their turn to become rookies in your franchise, whatever year you're in, you can just change their names, jersey nos. even heights weight birthdays.