There's an old saying, that "most times a good big man will beat a good smaller man." Today there was a great quote from Stan Van Gundy, coach of the Miami Heat basketball team. Referring to the strategy to run end-of-game plays through center Shaquille O'Neil, he said "As the game goes on, the quick guys get tired and a little slower, but the big guys don't shrink."
Of course, these things can always be reversed. Like Kato's quote from Ueshiba earlier on using hard against soft, soft against hard, etc., one could also use a strategy to wear out the big guys because it takes a lot of energy to keep them moving. Still, there is truth to the statements above.
Here's another thought, from my old Kenpo teacher. In a fight, hard stylists have an advantage at the beginning, but the longer it goes on, the more the balance shifts to favor a softer stylist. Why is this? The hard fighter will be fast and furious with a lot of initial power, but will tire out. The softer fighter will maintain a more even pace and become relatively stronger as time goes on. Ground fighting is like this too; the longer it goes, tne more important it is to conserve energy.