I believe it was a transitional time for warfare. Muskets weren't much better than earlier technology, their strength was that you didn't need much training at all to use them as opposed to a bow or sword.
In earlier wars, if often came down to whoever broke and fled first, a smaller army fighting for beliefs rather than a Lord could beat a bigger army.
But they undervalued newer technology that could cause havoc by relatively untrained people. It wasn't the same as WW1 where this really showed, but it was definitely on the way.