Uh hem. Those of us that dinked around with tennis in our youth generally speaking played on one surface, and one only. Depending on how advanced you got you might have a good idea of trajectory and speed and return angles.

That changes for every surface in the Grand Slam. It's not near enough to be a well rounded player, you have to be the best on EACH surface, and that is near impossible to do.

It's like the triple crown in horse racing. It's not impossible, but it certainly is hard. Can lead to a long time between being collected. It's really quite amazing when you really think about it.