I think it depends. People who are muscular tend to rely on their muscles when striking and grappling when all it really comes down to is technique and reaction. When I first started messing around with mma that was me. I was bigger and stronger than all the guys I worked with but even if they were smaller than me they knew how to use their weight to their advantage much better than I did and I would get worked. Its all about body awareness and once you use your body effectively you will improve greatly.