Deleted member 1487
Basically this says 'no matter how many troops the germans have it won't be enough' they were not ubermensch super fighters, but normal men and they could not accomplish miracles.
The author is being overly dramatic; I posted that to show a TL of events so we have an idea what we are working with ITTL.
http://en.wikipedia.org/wiki/Operation_Wintergewitter
Looking at the numbers involved the Germans were heavily outnumbered, yet they managed to get more than half of the way there, despite major delays. With the forces used in OTL in Tunisia, plus the 1st SS the numbers are roughly equal. Not only that, but there are other options, such as the one that Blair mentioned, which is an attack from another direction to pull the Soviet's attention away from the main axis of advance and make their job easier, while not putting more strain on the logistics of Winter Storm. Also the operation could jump off earlier if Blair's scenario where Fallschirmjäger seize the forward rail hub for the advance, making things much easier to set up.
Plus how quickly did the AAA rings get set up around Stalingrad? And bombers can be based further away were logistics aren't so strained and still operate in support of the attacks, including in support of the 1st SS if they launch a diversion for Winter Storm.