What does an insert on the face of a putter actually do? Is it all about feel, or will an insert change the force needed to move a golf ball?
I read an article on ‘dwell time’, and it seemed to say the addition of the insert did not make a statistical difference. Also, is my balata insert putter from the mid 90s still legal? You rarely see them anymore.
The dwell time does affect the way the ball comes off the putter and also how it feels. A really hard insert will tend to reduce the dwell time and it will feel as if the ball jumps off the face. If this is combined with a hard covered ball then it will also increase the distance of the putt, given the same impact speed.
There have been trends back and forth with regard to inserts and this will continue. Your soft insert (balata or equivalent) will continue to conform if it conformed when you bought it.
Overall performance is not dependent on inserts but will affect feel for certain putters which need to have some additional help to make them feel good. Putter performance is based on putter design which should focus on weight distribution, center of gravity location and certain physical dimensions and shapes. These will affect balance, stability and overall feel. When I designed the Frankly Frog Putter these were the elements that were most important. The Frankly Frog does not require an insert because it is machined out of a solid block of aircraft quality aluminum and has a soft feel.
Hope this helps,