Just prior to trying for the part of Chico Freddie, Isaac and the 3rd possible chico had to go to Canada to meet with Jack.
While there they saw Jack perform in the sunshine boys. I wonder if Jack ever saw Freddie's comedy routine.

Wow, that is an interesting question. I do not know for sure, but imagine that Jack Albertson did check out Freddie's comedy act at some point because they were such good friends and had a mutual respect for each other. I think Mr. Komack knew Freddie was the ONLY choice for the role of "Chico" and maybe Jack Albertson went to see him during a personal appearance or certainly after he won the role on the show.