Lawn Care Service of Cedar Park 100 E Whitestone Blvd Ste 148, #166 Cedar Park, TX 78613 (512) 595-0884
What I have noticed is that if you still have some medium-to-good players in your youth team by the first week of July, the "next big thing" will not appear. But if you promote him in the last week of June, then you will be able to have randomly your next big player, and the medium-to-good player that you have just promoted, he will disappear. It is strange, but it works (at last on my PS3).
So, my suggestion is that when you are in the last week of June, promote your youth players who have initial overall stats between 68-70, and save the game. After that week you will get your next big player after some reloads.
Just let me know whether it worked for you as well.