IANA Musician but rumor has it that Davis wasn't a great technical trumpet player, that he lacked the speed and range of others. The essence of his genius was in his understanding of the music and his ability to examine and re-arrange its principles.
It's worth considering in the discussion of the value of 'rock star' programmers.
He was something of a groundbreaking musician, establishing new concepts and then moving on to yet more new things, while others picked up his ideas and ran with them. His "Birth of the Cool" music, for example, really wasn't very popular at the time he did it. As I recall, the recordings weren't even released until years later, because it just wasn't expected to be well-received. In retrospect, it was great music, and helped set the stage for a whole sub-genre of jazz.
He was also adept at discovering / identifying great up-and-coming musicians and associating himself with them, to the benefit of both parties.
His sense of melody, arc, and color were second to none. I don't think he was totally without chops, though. He was playing faster and more agressive with his hard-bop crew.
Although note that the knowledgeable will have different ideas about who's important. You often hear variations of the phrase "an X's X" (i.e. a poet's poet, a director's director), and the same is true for trumpeters. While Miles was a solid player, he couldn't pull amazing melodies out of thin air at breakneck speeds like Clifford Brown[1], didn't have the virtuoso skill of any number of other folks[2], and had kind of a crap tone to boot[3].
3. Neither warm like Brownie nor powerful, like, say, vintage Louis Prima: http://www.youtube.com/watch?v=46byB2YGePA (solo starts at 4:25 and continues after the break). At least I think that was Louis Prima. It's been a while since I've seen the liner notes for that one.
Depends, he had classical chops and attended Juilliard briefly (in those days it was uptown by Columbia) and could produce beautiful tone in all registers, but critics have commented that he couldn't produce the dazzling topspeed runs that Dizzy Gillespie, Charlie Parker or Coltrane had, nor did he want to duplicate what anybody else had done.
It's worth considering in the discussion of the value of 'rock star' programmers.