The Master's Hands
The master's hands were usually cast at least in plaster, if not bronze. There was something magical about the hands that were able to write such memorable music. Famous piano composers each had their own peculiar way of grouping notes. This gives us some idea of what their hands must have been like.
Franz Liszt must have had extra long and unusually strong little fingers. His work relies on the little fingers of both hands constantly. He does this in a way that other composers do not feature. And his hand was very large.
Schubert Never Had A Piano Teacher
Schubert did not have large hands. Thus his accompaniment patterns can be downright maddening to learn. Many teachers have told me that Schubert never really had a piano teacher and figured it all out by himself. I seem to remember the term, "aberrant technique" in reference to Schubert's piano music.
But listen to the Schubert's Wanderer Fantasy. You'll have some idea of how good a pianist he must have been, crazy homegrown technique or not.
Hand Shape Determines The Notes They Pick
Brahms was an accomplished pianist, and much of his piano figuration is brutally uncomfortable. This leads me to believe that he had some peculiarity of anatomy that made such uncomfortable positions easy for him. Chopin had, by all accounts, not large hands, but used what he had to tremendous advantage.
Of all the piano composers, Chopin's demands on the hands themselves, as mechanical devices, are unending. Your fingers must all be of high strength. They will all be called upon at some moment to perform heroic, often unnoticed feats of strength and dexterity.
Chopin was the most natural pianist of them all, and took piano technique to heights which simply haven't been exceeded almost two hundred years later. In terms of usage of the human hand, there is Chopin, and there is everybody else.
Rachmaninoff Had Huge Hands
Pianists, who say his music requires a "chimpanzee" to play properly, often joke about Rachmaninoff. It's a remark probably due to the huge size of a chimp's hands, and is a tremendous compliment to chimpanzees everywhere. Schumann, of course, destroyed his hand in a misguided attempt to strengthen his fourth finger.
Weakness in the fourth finger is just an anatomical truth for pianists. It is a lame little digit that hardly belongs on the same team with brutal giants like the thumb and forefinger. So Schumann made a crude device out of sticks of wood and rubber bands, hoping to strengthen his fourth finger. It crippled him and ruined his career as a pianist.
Some Composers Were Not Pianists
Remember finally, that of all the great classical composers, only Berlioz and Wagner were not great pianists as well. Berlioz, genius composer of the monumental Symphonie Fantastique, was said to be able to play only three chords on the guitar. That was the entirety of his physical musical expertise! Maybe fingers don't matter at all!