One of the ESPN analists said about this, that if a pitcher blows his elbow or a pitching-related injury, it's not b/c of that one pitch, but a collection of all the pitches before that, and that that pitch is the straw that broke the camals back.
As sopme wise man once said: "A stonecutter will hammer away at a rock for perhaps 100 times without a crack showing in it. Then on the 101st blow, it will split in two. It is not that last blow alone which accomplished the result, but the 100 others that went before as well."