I’ve spent some time trying to figure this card out, and my conclusion is that Mack Robinson does not appear at all.
The two Black athletes are almost certainly Eulace Peacock (third from left) and Cornelius Johnson (on steps)
As for “Robinson,” he is actually (white) Fresno State Bulldog and 1935 AAU 800 meter champion Elroy Robinson.
More info here if you like:
https://1939bruins.wordpress.com/202...rd-that-wasnt/