A moment of inertia in Grasmere

I spotted the lawn roller at Lancrigg, a house associated with William Wordsworth. It has to be heavy to squash the lawn back flat. Surely that is weight, the force of gravity pulling down. But as it is heavy it has inertia that makes it hard to move forwards - Newton's Second Law shows that acceleration is inversely proportional to inertial mass. But the poor gardeners also had to contend with the rolling motion. Getting something to turn means getting mass to move around a centre of turning. The further away from the centre, the harder it is to move. The effect is called moment of inertia because it is a summing of mass x distance from centre. Where do you put the mass needed to flatten the lawn? For easy movement, you'd want more mass close to the middle. But it seems evenly distributed from the middle outwards as far as a wide rim which must mean the outside has even more mass if density is uniform.