Cameron Smith said:
It depends on the shot, and who is shooting .
D, C and B players miss shots because they are inconsistent. A players and above, miss because they dogged it or they were careless.
I disagree, B, C, and D, players as you call them are more likely to miss a shot or dog a shot they should and would easily make normally when they are put under any pressure at all. In fact it may define the way they play the rest of the set, they can go completely down the drain playing half their normal speed for no particular reason, they may do it even against a player they should easily beat. When you play on the road you depend on this happening, it is called "Lamb Killing". You give weight to an average player they can't possible turn down that on paper he should be able to win with and watch him s*&t all over themselves as you take his money. It happens almost every time.
Pro's on the other hand, may miss a shot here or there that they should make but it is more due to the fact that they don't live and die with every shot they shoot, not that they dogged it due to pressure. They don't want to overly pressure themselves worrying about trying to play perfect. You often see the best players in the world mess up position sometimes horribly and just play their way back in line like nothing happened.
Weaker players worry about everything, and rightfully so, since experience has taught them, or so they believe, that when the mess up it is just a sign of things to come. They actually start play hoping it won't but waiting for it to happen. You can see it in them when you watch them play, one missed ball or screw up at just the right time and they are done.. They don't trust their skills at all, that is partly what makes them weaker players and many never over come this self perception.
I think tournaments teach this, you have to lose gracefully. Gambling teaches you to be tough and gives you a more honest assessment of your skills. Years ago when players matched up and played till one player won, you learned that just because you are behind you don't have to lose. You learn the hanging in there can pay off and even if you end up losing you don't lose because you went down the drain but because the other guy was too tough and out played you, but you at least made a good accounting of yourself. You have a honest perception of your game, that is not based on wishes or hope, but of what it really takes to beat you, there in lies your confidence, that's what makes you a tough player.
When you know this going into a game it makes the game easier to play. You know it is possible you may not win but the other guy will have to be a hell of a player if he is to beat you. A lot of times when you match up with a stranger someone in the pool room will make the comment, "Aren't you afraid to play, you don't know how he plays, how do you know you can win"? The answer is I don't, but I know what it takes to beat me and if he plays anything less then that he going to lose it, doesn't matter who he is.