"Game improvement club" is a very broad term given to any golf club
or clubhead that is designed to offer less distance loss or less of a drop in
accuracy when the ball is hit away from the center of the clubface.
There are no measurements of the game-improvement capability of a club or clubhead
that can take all of the possible individual game-improvement design factors
into account.
In general terms with woodheads, the larger the head, the higher the clubhead's
moment of inertia about the vertical axis of its center of gravity, the larger
the face area, the shorter the length, the lighter the overall total weight
of the wood, and the higher the loft angle on the clubface, the greater the
game improvement capability of the wood will be.
With irons, the larger the head shape, the deeper the cavity on the back of
the head, the wider the sole, the more round the sole shape, and the more loft
on the iron face, the more game improvement benefit the iron will possess.
