In that film, the English cavalry is considered to be nearly indestructible, especially when facing the infantry that made up the bulk of the Scottish army. The horse riders' prowess was so evident that many of the Scottish warriors headed to the hills once they saw the combat would include fighting of this nature.
As powerful as the King's troops were, Scottish leader William Wallace knew they weren't as overwhelming as their reputation made them out to be. He realized the English would be overconfident and thus would be caught unaware when a tactical move (using long spears to offset the cavalry's charge) turned the tide of battle.
The Falcons could have a similar problem if they try too hard to lean on their running game in this contest. The overall statistics may say that a ground-and-pound attack is the way to an Atlanta victory, but a closer look at the numbers shows that Green Bay actually matches up quite well against Michael Turner and company. While the overall numbers do a solid job of indicating how each team did in the run game through the course of the season, they don't detail how their performance varied throughout the year.