Stubbing an iron means that you hit the ground too far behind the ball. This habit is on its very own list of The Most Frustrating Mistakes in Golf. Stubbing shows lack of commitment, pure and simple. It's failing to believe enough in what you're doing to follow through with conviction. It comes from a host of internal breakdowns, and it leaves a horrid taste in the mouth, a distinct sense of an egregiously wasted opportunity, and an immediate desire to fling the club - or the whole bag. It's basically inexcusable.