Dr. Dave has some studies on this that you might want to read up on.
I've read 100% of Dr. Dave Alciatore's website and am familiar with all of his assertions regarding the myths and magic of backhand english. They are from the physical standpoint correct.
Note, however, that if you exaggerate the angle in my diagram, one of those strokes can score a nearby object ball and the other would miss it. You can, likewise, point out the correct cue ball aim point and have a friend miss the shot while shooting through that EXACT point because their angle of approach is incorrect.
Or, consider it this way, since the point was made regarding a level cue. You can change the vertical approach plane of a cue stick to strike the exact same point as before on the cue ball and provide different effects on the cue ball such as jumping the ball or an exaggerated curve. Changing the
horizontal angle of attack through Point X can be as dramatic a difference as a vertical change toward Point X.
I get as much english striking closer to the cue ball with correct technique including soft speed, as mentioned already, as an amateur gets with a parallel "english" stroke and exacerbated squirt and throw.
I am most certainly insisting that the same degree of level cue, the same speed and etc. create two different paths for a cue ball when struck through Point X at different
angles of approach. We angle our cue stick by aligning it to a different shot line for the next shot . . .
. . . you can test my assumptions easily. Set a cue ball on a dead straight shot into an object ball three feet away at center table. First, hit through center ball on a straight full shot into the corner pocket. Next, place your body stance two feet to either side of where you would normally stand and stroke straight ahead and
through the exact same spot on the cue ball you struck the first time. You will miss the object ball entirely. You may even miscue the stroke.
Hitting a sheet of paper straight on can ball the paper around your fist. Hitting the same punch at an oblique angle can make the paper fly up and away without it crumpling.
One more analogy may help? I stand in front of you, facing you, my feet together under my body, touching along their sides. A punch to my midsection at my navel causes me to double over in pain. Ouch! A punch to my obliques or love handles may cause me to spin around instead.
Think of the cue ball as a spinning top, which it sort of is in this example. Strikes at two different angles to the same spot have varying degrees of efficiency regarding forward momentum and rotational momentum.
And I am unanimous in that!
