When a player goes on the disabled list, he is put on it for 15 days normally or more if need be. When the term expires, he goes back and is again an active member of the team. He can also be used as trading bait and can go to another team if they want him and resume his career on the new team. But the activation of the term on the disabled list must be kept. So, if a guy is on the 5th day of the disabled list, he cannot actively participate for the team until the full term of 15 days is over. You can always look this item up in the Baseball Encyclopedia under rules and regulations. Hope this helps you. You can go on line or go to the nearest library and get the full answer to your question.