When putting on slow greens, 8 to 10 on the Stimpmeter, is the old fashioned pop stroke better? I have trouble rocking my shoulders on long putts on public courses
Let me tell you that 8-10 on the Stimpmeter are not slow greens.
When I introduced the redesigned Stimpmeter in 1977 the average speed for country club play was 6’6”. For competition play 8’6” was considered average.
Greens that run to 10ft are still considered fast except for the US Open or The Masters where they can get up to 14 ft.
The answer to your question is that the “Pop” stroke was only good for Bobby Jones where the greens were about 4 ft and his putter loft was 8 degrees.
You need to maintain the shoulders, arms, hands and the putter as a single structure and pivot the stroke about the spine. This structure must not break down. If it does you will add sources of error, your consistency will be affected and certainly you will lose distance control.
If you are having problems in rocking your shoulders, try the left low baseball grip. Keep the left arm straight and this should become an extension of the putter. With this grip you will be able to take the putter back as well as all the way through the stroke with good rhythm.
Hope this helps