I've been researching NBA announcers, and i noticed that in 1968, ABC had "alternating coverage" of the 76ers-Knicks game with Chris Schnekel and Jack Twyman, at Convention Hall in Philly but at the same time had Jerry Gross covering the Pistons-Celtics game at Boston Garden. I wonder if this was taken form their Olympics playbook? Roone Arledge was known for this on the Olympics, so maybe he wanted it done with the NBA..... With signal being dlivered via telephone lines in that era(1968) i'm assuming that ABC had to use cues to alert the telephone company that a switch was coming.