Edward,
No doubt the occasional big screw up does happen around the green, but most of the time, for most of the holes, these strokes are going to be lost due to bad tee shots and ensuing recoveries.
Consider two scenarios for say a mid length par 4:
1) Player hits mediocre drive, after approach shot left 20 yards short of the green to the left. Even if the next shot is a skulled wedge that goes over the back of the green, the player is still left with something that is likely no further away than their last shot and still a chance to get a up and down for bogey.
2) Player yanks drive left OB or Lost ball in deep rough or bushes. Now they are sitting 2 on the tee and hitting 3. They have to effectively "par" the hole just to save a double bogey, and more thank likely it ends up as a triple or worse. Even in a scenario where they top the ball 30 yards off the tee, they now must string together 4 consecutive good shots just to save a bogey...also very unlikely.
In general the longer the shot, the bigger the punishment that awaits for lack of execution.