Being compact (read-short), while compromising your reach, opens up some interesting advantages as well. If you can dodge and weave your way inside to a taller, more "reachy" opponent, your shorter limbs put you in a great position of dominance. Your center of gravity is lower, meaning you are harder to take down and are able to execute takedowns easier. It's also hard to submit someone with powerful, stocky limbs and no neck
Matt Serra's only 5'6", and he's a nightmare to roll with! It's all how you use your body type. You have to implement a course of action that plays into your natural strengths, and keep the other guy out of his.
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"I have always said that if you need steroids to compete you are not a fighter. Fighting is all about heart, technique and capitalizing upon your opponents mistakes. It is not about putting something into your body and walking around with big muscles saying look at me. In my book if you are on steroids you are a loser."
Bas Rutten