Dear Gerald,
Actually, a side-on putt breaks the most -- a putt that starts somewwhere along the axis of tilt. If you identify the fall line through the cup, along which any putt is either straight uphill or straight downhill, the axis of tilt is perpendicular to the fall line. "Break" in this sense means the divergence of the ball's path off a direct line from the ball at address to the center of the cup. A side-on putt that starts on the axis of tilt has the largest "break" off the direct line of any putt.
Uphill putts, in this scheme, start anywhere below the axis of tilt, and downhill putts start anywhere above the axis of tilt.
Starting at a straight uphill putt on the fall line, this putt does not break any at all. As the starting position of the ball circles clockwise toward the axis of tilt, the amount of break increases steadily until the ball position is on the axis of tilt, when the break is maximal. Continuing uphill in the same circling clockwaise fashion, the break steadily diminishes until the ball position is again on the fall line for a straight downhill putt with zero break. This pattern continues to complete the cirle in a symmetric changing of the breaks.
The precise question you seem to be asking is whether a downhill putt from the 11 o'clock position breaks the same as a putt from the 5 o'clock position on the circle around the cup. The exact answer is a little bound up with the delivery speed of the putts to the edge of the cup. Assuming that both putts arrive at the edge with the same speed, both putts are aimed at the same target spot, which is a spot on the fall line ABOVE the edge of the cup. This means the uphill putt has farther to travel to the target than the downhill putt. I believe this indicates that the downhill putt from the 11 o'clock position has a greater divergence off the direct line than does a putt from the 5 o'clock position. And in general, uphill putts have less break than downhill putts.
I am aware that others believe that uphill putts travel faster at the start because uphill, and from this they believe that uphill putts break less due to ball speed. I think this may mean that the total TIME a ball is curving off a direct line may differ between faster uphill putts versus slower downhill putts, but I think that in reality the total divergence off a direct line from ball at start to center of cup does not ultimately depend on this difference. Uphill putts slow to the same speed at the edge that downhill putts arrive with.
Another factor that cannot really be assumed out of the equation is the tilt of the surface. Given a certain green speed and tilt combination, balls started downhill will continue rolling solely from gravity's overcoming any friction. In these situations, the golfer can finess the break by putting the ball downhill over to the fall line, and after that, the downhill rolling runs straight. These putts can't really be considered in answering your query.
So, my short answer is that downhill putts break a little more, but that is because both downhill and uphill putts are aimed at a target that is above the cup on the fall line.
Whenever I think about sinking a breaking putt, I just consider a side-on putt to present the maximum break.
Cheers!
Geoff Mangum
Putting Theorist and Instructor
PuttingZone
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