I think a lot of people would be highly surprised at just how innovative they were in the medieval ages tactics/strategies/arms development wise, and indeed just how rapid some of them were when need demanded, as for instance the English tried out no less then three different tactical possibilities against the Scots between Bannockburn and 1337.
Likewise such things as flanking maneuvers, feigned retreats and much more such as holding units in reserve while others pursued a beaten enemy etc had been in widespread use well before then, and so let's hope were able incorporate some of those without making things over complicated.
Finally someone that gets it. The medieval age wasn't characterised by a lack of tactical flexibility or thought, the real problem was that you didn't have large amounts of professional troops, thus tactics were dictated by what you could achieve with poorly trained men. Even the trained Men at Arms and Knights were more focused on training on a individual level then training as a unit. Within those parameters they were quite innovative and as we get to the end of the age and the beginnings of what we would see as modern style professional armies suddenly they had a lot more options to utilise.
