The slice backhand, one of my favorite shots.
The general assumption is that it is an easy shot to hit. I guess that may be due to the fact that for some blocking the ball is equivalent to hitting a slice backhand. A hacker on the public courts does that and he or she thinks they are slicing. They are NOT.
BEAUTY & PERFECTION
There are some things in sport, like formations in football and edges in figure skating, that only a select few who know enough about the sport can really appreciate. A slice backhand is one of those things. I recently had to explain to a friend what makes the slice backhand a beautiful shot. I had to think about this before responding. Knowing that my friend is a figure skating fan, I thought this might make sense. The best slice backhands trace a pattern, just like a skating blade does in completing a school figure. The pattern that the best slice backhands trace in the air is that of an S-curve. The racquet starts out at shoulder height, moves across, down and out in front of the player's body.
DEGREE OF DIFFICULTY
In order to trace that S-curve, the player must have amazing racquet control. There is a point along that S-curve (i.e., two consecutive curves in opposite directions), for instance, where the failure to close the face of the racquet can lead to the ball taking off. That point would be at or slightly after the apex of the first curve.
A flexible and universal grip. I use a Continental Grip on the shot. I think Steffi did as well. The more western your grip is the less absolute control one has of the face of the racquet. Hence, the more difficult or tame the shot becomes.
Players who use a western grip on their forehand have the tendency to address the ball with the racquet face in its horizontal position, even if the grip on the slice backhand is more open. That's just something I noticed recently. With the racquet in that position, the swing won't fully complete the S-curve. After the first curve that is, the racquet stops moving down and out toward the net. Instead, it usually moves out to the side, on the backhand, left to right.
The brilliance of Steffi's slice backhand is that it traced the complete S-curve. Moving the racquet from low to high (first curve) would only have allowed her to float the ball over the net with a moderate amount of pace. It is the second curve, not the first, that makes the ball go faster and bite into/skid through the court.
WHERE HAVE ALL THE GOOD SLICE BACKHANDS GONE?
Most of the blame rests in the grips today's players use to hit a forehand and a double handed backhand. The Western grip on the forehand over time renders even the best player's wrists inert. On the two-handed backhand side of today, the left hand and wrist is more active than the right hand, causing the right hand again to become even more innert.
Therefore, by the time the best players start to learn how to hit a slice backhand, they no longer have any feel or real flexibility left in their right hand or wrist to really complete the S-curve as described above.
That's my theory.