Originally Posted by Merton
Apples and oranges. Grass is different than hard court, the movement, ball bounce are different. Court speed is only one parameter among others.
Borg 5 times winner at Wimbledon and 0 times at US Open. The surfaces are totally different.
Ball bounces higher on the hard US Open surface.
Bounce more reliable on the artificial surface of the US Open.
Firmer footing on the US Open surface.
Use higher pressure balls.
Not to mention the crowd
Grass, hard and clay are 3 totally different surfaces. Some have struggled to master more than 1 surface, many have mastered 2 and few have mastered all 3.
Borg mastered grass and clay - hard court problems.
Lendl mastered clay and hard - grass court problems.
Sampras mastered grass and hard - clay court problems.