I certainly didn't expect this:
Several things played into this outcome.
My opponent's air war didn't go well. Not knowing the particulars of the AD settings, all I could surmise was that interdiction wasn't as heavy as I expected, and consequently German forces in the center were able to fall back in good order to natural barriers.
The rain on turns 3 and 4 hurt the enemy air efforts, and also helped slow his tanks. Once released I used my security units as a matador's cape, in an effort to induce enemy advance along the axis I preferred.
The Allies also utilized their Armored divisions more as battering rams than letting the infantry do the heaviest lifting and then utilizing the armor in an exploitation role.
Finally, the ability to group my panzers near the depot at Le Mans allowed them to recover sufficiently for the decisive counterstroke against the enemy's thinly defended line joining the American and British Army Groups.
Even at this late date the Germans have several high morale units that can plunge deeply into enemy territory at only a +1 MP cost.
Bocage is fantastic defensive terrain, but with no units in it tanks move across it like clear terrain. A handful of divisions broken down into regiments and staggered in reserve would essentially preclude a result like this.
I'm currently replaying the scenario as the Germans with Harrybanana, suffice to say with better Allied air interdiction, and better initial weather, the results are quite different. A more detailed AAR will follow that games conclusion.