I'm just curious here as to why you're still calling them the Devil Rays lol. It's been like 7 years since they changed their name!
To answer your question, I believe the players have to sign papers saying they can be put in the game. Last year Jonathan Schoop didn't sign his papers right away, so he wasn't put into the game until the 1st or 2nd roster update (He played the year before, so he would've been on the default roster if he signed his papers).