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.