Why were Murderers Row ducked so much?

[Vendettos]

I don't really understand it, they got ducked a lot but the people who ducked them went on to fight the Jake LaMottas and Archie Moores and Rocky Marcianos of the time, who are in my book just as, if not more tough.

It seems in my ignorance towards the Murderers Row as a whole, focusing only on the fighters individually I have missed the politics of it, as I assume race had a part to play, considering Charley Burley only ever held the World Coloured Middleweight Championship, a title thats name seems embarrassing today, and shows how ludicrous the whole race thing was.