Quite commonly pool is compared to a long list of other games that we play with sticks and balls-golf, tennis, baseball, polo, etc. In those comparisons, people often go a step too far in pointing out the similarities, usually overlooking the one, prominent difference that sets pool apart from all of those games. What is that? Very simply, only the cue sports confront us with more than one ball. And any eagerness to align pool too closely with the basic approach to other stick-and-ball games can easily lead to a harmful over emphasis on the cue ball and thus losing its proper role in a shot. But that's a topic for another column. For our purposes now we do well to remember that, while other games demand control over the ball with a stick, we, as pool players, begin the same way toward the ultimate, and seemingly insane, purpose of controlling a ball with another ball. Add a third ball to the mix and you have a regular riot on your hands.
In the diagram we have two combination shots that are not lined up for the pocket and thus demand cutting the second ball with the first ball to pocket it. For both shots we're assuming that we must play position for the first ball after making the shot. When the line of centers for a combo does go to the pocket, and the cue ball is on or close to that line, we play a stop shot to get the next shot on the first ball, which remains on the line for easy position. Here however, because the shot is not lined up, the first ball will not stay close to the same pocket. Instead it will move off of the line of centers to go somewhere away from that pocket.
First, we have shot A, the combination with the two solid balls on the long rail. For this shot, position on the first ball is relatively simple as long as we remember to consider where it's going after hitting the second ball. With ball in hand I would place the cue ball where it's shown, slightly closer to the rail than the dotted line of centers, and so that's the position I would play for from the preceding shot. A cue ball closer to the cushion would be better than farther, and that's the side I would hope to err on if I did not achieve my most desired position. Our ideal position is set up to shoot straight at the first ball to facilitate a stop shot that leaves the cue ball a comfortable distance from the rail for the next shot. The most important point to note is the path of the first ball as shown with the solid line. Because that first ball is moving across the table we must manage the shot's speed to set up an easy next shot in the top left corner. If the cue ball were considerably farther from the rail, in the vicinity of the dotted-outlined ball, position would be trickier. In that case one would have to determine just how much the first ball must cut the second one to pocket it. If the combination's angle is nearly straight, the first ball will not stray too far from the bottom long rail, so the rebounding cue ball can land in position to shoot the first ball into the same corner pocket. When the cut angle between the two object balls is thinner, the shot demands enough speed to move the first ball across the table and close to the top left corner because the cue ball will go in that same direction after it rebounds from the cushion.
Although shot B is virtually identical, its position on the short rail brings greater difficulty regarding position. Let's begin with the ideal cue-ball position from shot A, as shown with the dotted-outlined cue ball. What's ideal for shot A on the long rail becomes a headache on the short rail as the first stripe now heads toward the top side rail where there would be no easy next shot with a cue ball that stopped on contact. One would either have to control the first ball's speed and direction precisely enough to leave it in front of the top side pocket or follow the cue ball to the top side rail for a difficult next shot all the way up to the top left corner. With ball in hand I would place the cue ball away from the short rail where we see the solid outlined cue ball. From there one can hit the cue ball with follow to rebound it from the short rail out to the X while the first object ball rolls to the top side rail into the vicinity of the arrowhead. Another option is playing the shot from the position of cue ball C and rolling directly to the X, but shooting the combo from there can make pocketing the ball too difficult. In any case the shot is far from easy.
When we consider how difficult it is to hit an object ball precisely enough to make a pool shot, it's almost disabling to think about how frighteningly small the margin for error becomes when we must shoot one object ball into another to pocket that second one. When I was young my father told me that, no matter how easy they look, combinations are always tough. At the time it sounded a little scary, but I know now that it was an understatement and a directive to study this uniquely challenging family of shots.