What makes a good hard court player?
It is easy to think about a prototype player on clay courts or grass courts. A good clay court player needs to be extremely fit and able to last a while in long rallies by getting to every ball and making few errors. Preferably, they should put a lot of topspin on their shots. A good grass court player will traditionally have a monster serve, great volleys, maybe a wicked slice approach shot, and be great at passing shots.
Those are sort of easy and unique players. One would never confuse a clay court player's game for a grass court style and vice versa. But what exactly is unique about hard courts and therefore what makes a good hard court player?
First off, who are the best hard court players? Federer has won 8 slams on hard courts. Sampras won 7, Agassi won 6, Lendl won 5, and Edberg won 4. All of these players won both the US Open and Australian Open on hard courts multiple times.
What do they have in common though? Federer, Agassi, and Lendl are mostly basline players, while Sampras and Edberg were serve and volleyers. Sampras, Federer, and somewhat Edberg have very good serves, but Agassi did not have a particularly good serve. Lendl hit with a lot of topspin, as does Federer, while Sampras for instance hit a lot of flat shots. All these players were all time greats so they all moved very well, especially Federer and Lendl, but this isnt a list of the VERY best movers in the open era.
To me it seems like there is no prototype for a good hard court player. There is nothing unique about hard courts that gives a certain playing style an advantage. The court doesnt take as much spin as grass and clay so slicing doesnt work as much as it would on grass, and topspin isnt nearly as effective as it is on clay. The courts are slower than grass courts (although these days the US Open might be as fast as Wimbledon) so big servers don't dominate, though they do well, especially at the US Open. Because hard courts are faster than clay courts, rallies don't last as long so fitness and supreme movement are not quite as key as they are on clay (though of course movement is key in tennis no matter the surface). Players come to the net some on hard courts, but not as much as they do on grass, so extremely good volleying skills are not as important. The ability to slide on clay courts and not slip on grass courts are important in movement, but there is nothing special about movement on hard courts that takes practice.
The only tactic that I can think of that is somewhat unique to hard courts in its effectiveness was Agassi's return of serve. Agassi would take serves very early in order to make a quick aggressive return. This was possibly his biggest weapon. It was most useful on hard courts, though, because hard courts always get true bounces. Grass courts and clay courts frequently get very weird bounces, and if you are taking a serve early, you won't have time to react to a weird bounce and you will likely mishit the shot. On hard courts, that doesn't happen, so taking serves early is most effective there.
Other than that though, I cant think of anything that is a hard-court-tactic or any attribute for a player that helps them a lot more than other attributes on hard courts.