The pro circuit was show business. Kramer recognised this. So you needed an underpinning 'story'. It was exactly like P T Barnum, or Wild Bill Hickok and his Wild West show.
The 'story' in the early 50s was could the upstart Gonzales overturn Kramer - 'roll up, roll up and see if he can'. Then, when Gonzales was top dog there was the new American, Trabert, so still interest for North American crowds. Then he struck lucky and got the two new wunderkids, Rosewall and Hoad from under the noses of the authorities. Great new challenges for Gonzales, especially Hoad who was the golden-haired Adonis. Eventually even they, and Gonzales, were 'old hat' so he needed a new story, and he got Laver. So now the story was again could the new kid topple the old guard.
But then Gonzales got older, Hoad injured, and older, and there were no new challengers, especially American. So the story got a bit stale....and then Open Tennis galvanised everything again.
So it wasn't so much that Rosewall and Laver were not box office, it was that the 'story' needed new blood, and it never happened. Of course they weren't as big box office as Gonzales (American) and Hoad (Adonis) had been, but they must have had some sort of draw, otherwise how did they captivate an American audience like they did in 1972 in Dallas?
In fact in terms of great box office 'draw', by which I mean drawing people to watch tennis who wouldn't normally, then there have been only a few, if my tennis history is correct, and off the top of my head they are:
Tilden and Lenglen (definitely)
Riggs (maybe ?)
Gonzales?
Hoad
(Nastase I don't think was quite big enough to be a draw outside tennis fans)
The Big Three (Borg, McEnroe, Connors)
Becker ?
Other players have been big in tennis, and well known generally, like all top sportsmen, but the above are the only ones I can think where people went to see the person, not their play, and even then I am not sure how big a draw some of them were
Hoad and Gonzales made piles of money in 1958 and 1959, Gonzales about $100,000 in 1958, Hoad about $200,000 in 1958 and well over $100,000 in 1959, enough for him to semi--retire.
In the 1960's, Laver and Rosewall made less money than Emerson and Santana, as the amateur managers got into serious war with the pros.
Ridiculous.