it all depends on when the order is given. If it is given as soon as the Soviets break through the Romanian and Italian divisions ,then the 6th Army can conduct a fighting withdrawal. It will still take time to disengage with the Soviet 62nd army and plans must be in place to supply the army on the move. Also the Axis must move forces to defend the river crossing at Kalash to keep the AG from being cut off. The 6th must make a stand at some place to keep the Soviets from Rostov so as to not let them trapping the Caucus forces, which would have been a bigger disaster then losing the 6th Army.I would rather have had the Germans take Stalingrad on the bounce after they broke the Soviets on the Don and then crossing the Volga to take Saratov ,thus cutting off the whole caucus rather than splitting off the armor to go into the south.