Where did the belly putter come from?
According to my understanding, Paul Runyan and Phil Rodgers created the belly putter a few decades ago. Runyan had always been one of the top putters in his day and had a long distinguished career teaching golf, and especially putting, in Southern California. Runyan created a split-hand grip (right hand low) and stood fairly tall, so he had a longish putter. Rodgers stuck it in his belly. Voila! Al Barkow co-authored Phil’s book on golf instruction, Play Lower Handicap Golf, in 1986, so as usual Al Barkow will have to be the final arbiter on this matter of golf history. What recommends it? In a word – steadiness. The point of the belly putter is that by resting the butt of the putter against your belly, you stabilize the pivot in the stroke. (Some people erroneously call it the “fulcrum.”) The pivot is the point above which nothing matters. In this case, that means the elbows, shoulders, and head. So long as your belly doesn’t move about during the stroke, your pivot will be stabilized
