Your are correct. If they are activated they can be placed on the major league disabled list. But then you are paying them a major league salary and benefits, as well as giving them valuable service time to get them closer to arbitration. I don't think teams go this route unless absolutely necessary. I think in Burdi's case he is probably consider on the active roster due to the Rule 5 distinction, so he could be placed on the 60 day list. In Chargois case, the team avoided activating him and placing him on the 60 day almost all season and had to release other players from their roster during the season in order to activate others to fill team needs, which shows what having that spot tied up causes. They would have had the same situation again this year if he was still unable to pitch to start this season. I think they have determined that those spots are just too valuable to have tied up with players that are unable to perform.