By the results, Imagawa seems heavily favoured, yet the sides are near identical, as are the Command Cards.
1 additional Mounted Leader plus 1 extra Dragon card wouldn't make a such a significant difference.
I suspect it relates to the Oda concentration in the Centre, so good Centre cards would be the key.
“I dreamt of worldly success once.”
― Miyamoto Musashi
Oda obliterated 6 (3+3) - 2 (1+1) and the future looking very dark. Even though both have the same army, Imagawa has the advantage of DC, honor, leader, terrain, deployment and the cherry on top : first turn. They can play offensively on their right wing or defensively on their left. Still a matter of dice and cards, Oda have the odds against them but nice scenario nonetheless.