Iron performance can best be measured, not only by the quality of shots produced by well-executed swings, but also by the quality of shots when less-than-ideal contact is made with the ball. From an engineering standpoint, the key to maximizing shot quality on off-center hits is weight distribution. Club designers learned that by placing more weight around the perimeter of the club they could reduce the amount that the club twists on off-center hits. When the clubhead is more stable, off-center hits still fly relatively straight and far. However, perimeter-weighted irons had an intrinsic drawback. In order to redistribute enough weight to exact a measurable performance advantage, the clubhead shape had to change.