Good wrestlers do well at MMA for multiple reasons. Competing at the highest levels two individuals struggle hand to hand with each attempting to subdue or unbalance the other. As simple as it sounds the techniques used and strength and endurance needed to be successful take years of training and working out to even be able to compete at high levels and only those that can comprehend how fatigueing wrestling/grappling really is can appreciate and understand why wrestling is arguably the best discipline in MMA.