I never got to see the late Paul Bley perform, but several times in the late 70s, I did get to see his by-then ex-wife, Carla Bley, who had previously composed Bley's signature Ida Lupino.
With their narrative and almost cinematic compositions, Carla Bley's records still sound more like rock records to me than jazz. An album like 1979's Musique Mechanique was not a big leap for fans of prog-rock bands like early Genesis and Yes, or for those accustomed to the big-band arrangements of Frank Zappa. Her compositions from this period were fairly simple rhythmically, often based on 4/4 marches - no complicated jazz drumming to confound the audience - and her soloists may not have conjured the nuanced emotions of the finest jazz, but the solos were loud and brash and suitably epic. In other words, just the thing that rock audiences ate up.
When Carla Bley and Her Very Large Band played Boston's Paradise Theater, a rock club, the audience treated them like rock stars, enthusiastically calling out the names of soloists ("Windo!") and dancing in their seats (this was when rock clubs still followed the cabaret model of seating the audience at tables with a two-drink minimum).
Bley's most famous composition is probably the more adventurous and avant-garde Escalator Over The Hill, an operatic magnum opus that sprawls over three bizarre discs that she composed with the Canadian drummer Paul Haines. Another rock connection: Paul Haines' daughter, Emily, would later go on and become the songwriter and lead singer for the Toronto band Metric.