First of all, this team, or it's players is not 'done'. Come on, sure we have played terribly lately. The thing is though, the Lakers won by what, one point, and the Magic by a basket or something close to that. Those are two excellent teams that barely won. KG looks really bad now but he will progress barring further injury. If team doctors thought he had a good chance of reinjuring the knee then he would not be playing.
Jamison does two things to help this team out tremendously. He does provide a good backup for KG and also is an inurance policy in case he does get reinjured. If Jamison plays then we have a contingency plan and even if KG doesnt get hurt again he will have the time he needs to heal.