Steffi's game had both orthodox and unorthodox stroke production. Her serve, while hit with a high ball toss, was technically perfect. One thing that people usually didn't notice with Graf, or took for granted, was how fast she did everything. She is the fastest player to ever have played women's tennis (most of the all time greats will back me up on that), and with her serve, she snapped at the ball very quickly. To have a high ball toss and hit the ball while jumping up off the court and to be able to time that wrist snap took extraordinary talent, which she had in abundance. Holding 2 balls helps maintain the consistency of the ball toss- I recommend everyone try it for a few matches- you'll see!
Her backhand slice and topspin were classic strokes- probably one of the top 5 slice backhands in the history of the sport.
The Graf forehand is unorthodox, but that does not mean technically unsound or inconsistent. She hit it off her right hip, and in comparison to the conventional theory- it's late. This was one component of why it was so effective- she took the racquet back many times only at the last second, and then jumped up off the court and hit it like a sling-shot with extreme wrist snap- just like her serve. When you think about it, the serve IS a high forehand.
Her biggest weapon, the one that allowed her to produce all those great results, was her footwork. No one in the history of women's tennis has run around more backhands to hit a winner than Steffi Graf.
The true test, in my opinion, is whether a player using the new, bigger composite racquets could play and win with a wooden racquet. Steffi's game would be just as dominating. Monica Seles wouldn't have won a single major with a wooden racquet.