It is very important to apply scientific method to the evaluation of outcomes, especially if one might be called upon to advise others. It is no good having theories if that's all they are - one needs a proper and robust methodology to establish cause and effect to a level of statistical certainty.
Take my garden. Earlier in the summer, I postulated the theory that the reason I never saw Whisky tearing around like his tail was on fire anymore was that the grass had grown too long. Rather than breaking into a run, he had to cross it in little bounds. My solution? I mowed a strip across the lawn and up the edges. Result: Supersonic Whisky.
Now it's no good me just telling you about this one-off event and asking you to believe it as a general rule. I must demonstrate that the experiment is repeatable. Well here we go, several weeks on, the strip of grass has grown to about 6 inches high and the bunny is back to bounding and ambling. Step one: Mow new strip adjacent to the old one. Step two: Add bunny and observe.
Conclusion: Bunnies' behaviour adapts to their environment. If you don't see them racing about and binkying it may be their area is too small or the floor is too slippy or just not good for running on. Give them large areas with a good straight-line distance and great purchase for high-speed feets and you can sit back and watch them fly!