If you have a weak backhand, you will need to strengthen it. If your serve is flat and erratic, you will need to develop reliable spin serves. If the only time you come to the net is to shake hands at the end of the match, you will need to develop approach shots and volleys. If your one handed backhand doesn't permit you to hit topspin, you need to learn to come over the ball. If you hit a two handed backhand, you will need to develop the one handed slice.
Pace is an often times overlooked dimension of the game.
When they win, they win big. Yet, a player like John McEnroe would decimate these players. Mac is a player who uses all three-power levels to their maximum effectiveness. Despite his on-court histrionics, John McEnroe is truly a genius with a racquet. He can and will hit the big serve.