[jim_0068]

There is compression but it is very very small. Also the clubhead should travel in an arc on a natural putting stroke, unless you setup for a square/square ala Pelz stroke.

However i read, somewhere, that the small compression the ball when struck by the putter IS IMPORTANT because of where you hit the ball to compress it.

I read that this is why you want a slightly descending blow because that small compression helps to "bounce" it out of its depression that the ball is sitting in on the green and reduces "excessive" skid.