Do you think a small person no matter how skillful he is, still has trouble fighting a guy many times his size?

Let's ume a Wing Chun master like Leung Ting (5 ft 8) fighting the average MMA or UFC fighter (6 ft 5 guy). So, my question is although skills in the martial arts can compensate for size and power disadvantages, there are still limitations as to what one can do in a fight.