CrapGame, You seem to have hit it on the head. The Sherman is a weak tank. The Sherman was at best, marginal. It's total weight was dictated not by tactical concerns but by dockside crane capacity. So armor was marginal by mid-war standards.
Nonetheless, it was a good tank, not a great tank, but a good tank. It's all a matter of how it's employed. You mentioned that your tanks advanced in a "Diamond" formation. When I played that scenario, I paid no attention to any formation at all. I sent three tanks (including the plus) to the left and two to the right of the road. My two tanks on the right got nailed by the Stug's as soon as the got to the edge of the woods at the top of the hill: Blam, Blam. I suspect this is exactly where you got drilled. However, my heavy section raced at speed for hull down positions at the base of the ridge on the other side town (where the Stug's where). Then I had them creep up and zap all three Stugs quicker than greased lightening from hull down positions. End of Stugs.
The problem I had was in the heavy woods just to the left of the Stugs. There is a victory point there and I had a reinforced platoon assault it and the siezed it but were counter-attacked and eventually were wipped out. I ended up barely holding my position and commited my reserve infantry platoon who vanquished the fell foe and enabled us to gloriously triumph and decimate the Hun completely.