Bryson DeChambeau, the mad golf scientist, has ruined it for everyone.
What about those of us who didn't exactly tear it up in high school physics class?
Good news is the golf-geek engineers at all the equipment companies have figured it out for us.
Three letters changed the shape of golf -- Moment Of Inertia -- aka MOI.
MOI is why driver heads have gotten bigger and more sophisticated with their makeup the past decade. MOI is what we don't use balata golf balls anymore. MOI is why all those nice little Bulls-Eye putters have been banished to our old golf bags out in the garage.
MOI first came to light with drivers. It was all about more speed, balls coming faster off the club-face, more distance -- yeah baby! The last frontier for MOI has been the putter. It is the reason that putters have gotten bigger, wider with more sophisticated engineering in the development process.
The science behind all of this tells us MOI is a good thing and the more the better:
To get scientific on this, and we don't want to but we will, there are two main MOI features that can be measured for the clubhead itself.
The first one is demonstrated when you hit a shot off the center of the face, (or miss the sweet spot). Even though the head is secured to a shaft, the head will try to rotate around the vertical axis going through the club-head's center of gravity. In marketing terms, this is the head design property that has a bearing on the amount of "forgiveness" a club-head offers for off-center strikes. The larger the club-head, and/or the more the designer incorporates perimeter weighting, the higher the MOI of the club-head about its center of gravity vertical axis will be, and so, the more forgiving it will be.
The higher the MOI of the head about its vertical CG axis, the less the head will twist in response to an off-center hit, and the less distance will be lost from that off-center hit. The additional head response from the off-center hit is to divert the face direction from the intended line which means a loss of accuracy as well.
The second MOI effect occurs, as the golfer swings the club. During this motion, the club head will attempt to rotate around the axis through the center of the shaft. This MOI is crucial in maintaining face direction throughout the strike. A lack of MOI during impact means less stability which means more difficulty keeping the head square at impact.
Now about the size of those drivers and new putters: The smaller the head and the more head weight that is positioned close to the center of the head, the lower the MOI of the head will be around its vertical CG axis, and the more distance will be lost when the ball is hit off center along with the loss of directional accuracy.
With the new drivers and putters, it's the opposite.
A larger, more forgiving impact area or sweet spot “area” means you DO NOT need to stress and over-control the putter in order to make good contact with the ball. More forgiving means more stability which means the face will stay square with less micro managing on your part. These two elements alone are the essence of good putter to ball contact. You can NEVER have too much of this. However, not enough of this which is the case with most putters, translates into a tedious over-controlling stroke that activates the parts of your swing that may seem to be the most reliable, your dominant small muscles, but are also easily distorted under pressure. This is what opens the door to the yips which is an understandable progression if left unchecked. Sub-conscious manipulating and second guessing adds a new dimension to what would otherwise be a basic movement.
Did you get all of that. Of course, DeChambeau would but he was a physics major at SMU.
One final thought in all of this is that some people think there can be too much MOI.
Some companies and even some instructors, will say that there can be such a thing as too much MOI.
That’s like saying there can be such a thing as having too much money.
In any case, pay attention to the new putters. Do your homework, try them out.
And just remember -- you WANT that MOI -- you NEED that MOI