Like Penchant, this is also something with which I'd take issue. Going from the historical point-of-view, there are many examples of smaller medieval nations/armies defeating larger ones. In BM, there's no possibility to do anything akin to the Battle of Sterling Bridge (5000 English killed because the theoretically weaker Scots used unconvential tactics). It's been said a few times that BM doesn't simulate unconventional tactics because most battles took place by prior arrangement on a fixed field of battle, but even then there are historical cases of smaller armies defeating bigger ones (e.g. Agincourt, famously). Something which is impossible in BM.
There are numerous cases of smaller armies defeating larger armies in BM. A highly trained 30-men SF unit would trounce a badly equipped freshly recruited 100 men archer unit. Conveniently, however, the SF unit would also have a similar or higher CS value. The calls for a smaller army to be able to defeat a larger army are not related to medieval examples where small number of men beat a larger number; they ask for more differentiated tactics to be available in the face of a high CS differential.
