A mallet style putter (which is the most forgiving putter design) with a flat sole from toe to heel or one without an upward tail taper will affect your performance depending on the length of the fringe or the degree of side slope on which you are putting.
An airplane has an upward tail taper to prevent tail-strike during takeoff and landing. A mallet putter with the same design concept will prevent dragging and snagging on the back and/or forward stroke when putting.
To prevent a toe or heel snag contact with the ground when putting on a side slope, the putter design must have a toe/heel radius. This radius will also accommodate small changes in putting styles with slightly different lie angles.
These innovative features which I incorporated in the design of the Frankly Frog Putter are essential in mallet putter design to remove all the potential sources of error.