When we are playing poorly, the search begins. The better players--or at least the most intelligent players--know enough not to immediately start messing with their swings when the wheels come off. This is because a swing that generally produces reasonable results isn't likely to be the culprit. Often what is wrong is something simple. And this is why good players look to the basics when things go awry. They check their alignment and ball position first.
Consider what Bobby Jones had to say on this subject in his book Bobby Jones on Golf:
"One reason golf is such an exasperating game is that a thing learned is so easily forgotten, and we find ourselves struggling year after year with faults we had discovered and corrected time and again. But no correction seems to have a permanent effect, and as soon our minds become busy with another part of the swing, the old defection pops up again to annoy us.
This is especially true with respect to placing the ball in the position of address. Apparently of little importance, this is one of the most vital considerations in hitting a golf ball, not that one position is correct for every player, but because for each player there is one position which, with the peculiarities of his method, enables him to hit the ball most easily and most effectively.
In my particular case, this position happens to be at a point about opposite the middle of my left foot, and this is true when using any club for almost any kind of shot. Of course, the exigencies of a peculiar situation may alter this position to some extent, but normally it remains the same. With the ball in this forward position, all of the power of the stroke can be applied behind the ball; there is no additional tension and loss of power because of a position which requires the player to hold back in order to meet the ball squarely.
It is not difficult to see that if the swing is adjusted to strike the ball in a certain position, even a slight variation in the position of the ball, the swinging remaining the same, will cause an error in hitting. No golfer needs to be told what ruinous results may follow from even a small mistake. Taking the ball an inch too soon or an inch too late may throw it many yards off line at the end if its flight.
Placing the ball at address should always receive minute attention. Too many times we step up confidently and carelessly to play a shot, and fall readily into a position that feels comfortable and is, we think, the accustomed attitude. Without giving the thing a thought, we hit the shot and are at a loss to explain the pull or slice that results. A tiny error is enough, and it is very easy to overlook."
Bobby goes on to relate a story about how a friend of his helped him at the US Open at Winged Foot in 1929. He was hitting everything to the right and, try as he might, he couldn't figure out what was wrong. His friend, T.N. Bradshaw observed that Bobby seemed to be playing the ball farther back in his stance than usual. Bobby moved it forward in his stance and had no more trouble. He concluded by writing:
"A slight change of position is hard for the player himself to detect, especially if he plays for any appreciable time that way. But to move the ball interferes not at all with the swing. To try a different position endangers no e of the elements of touch, timing, or rhythm. And very often it will be found to be the exact adjustment required. It is impossible to contend that the same relative positions of ball and feet are proper for every player. But if anyone is off his game, it will do no harm to experiment-- to shift the ball nearer the left foot to correct a slice, and nearer the right foot to correct a hook. If it works, it is the simplest specific that can be given."
It is worth noting that most amateurs tend to play the ball too far back in their stance. To get the most power and accuracy from the shot, you must be behind the ball so you can drive it forward. So, if you're having trouble, perhaps you should check your ball position. As Bobby said, it can't do any harm.