Rosewall was interviewed for the Boston Globe a few days after the end of the tour with Hoad and Laver. The interviewer mentions that Laver lost 8 matches to Hoad in the recent tour.
If Laver actually lost 13 matches to Hoad, Rosewall would have known it, and would likely have corrected the interviewer.
February 6, 1963 (Wednesday)
At first Ken Rosewall wanted to sweep Rod Laver’s pro record under the nearest rug. Then he confessed.
Against Lew Hoad, Laver has won none, lost eight. Against Rosewall, he has won two, lost 11. Grand total: two victories, 19 defeats.
“Worse than the New York Mets, the New York Knicks and the Boston Bruins,” I muttered.
“But good for tennis,” said Rosewall.
“You mean pro tennis, don’t you?”
“For tennis generally. We showed the pros are still the best, and we showed those who said we’d protect Laver that pro tennis is honest. We all want to win. We don’t carry anybody.... I’m playing well. In New Zealand, I got hot and won all seven from Laver, three on grass, four indoors,” he said.
“We drew well—50,000 in eight big-city matches in Australia.”
... He hopes his trip to this country ends as auspiciously as it began, explaining, “I left New Zealand at 8:30 p.m. on Sunday, and arrived in San Francisco at 5 p.m. the same day.”
He gave due credit to the international dateline.
If Hoad beat Laver 13 times in this tour, a few more questions have to be answered. How is it, for example, that only 8 of the victories were reported to the worldwide press? These matches were public, obviously, and the local press Down Under would surely have the correct tally. So how did the worldwide press end up with a score of 8-0?
And once that happened, why did no one, including Rosewall on this occasion with the Boston Globe, correct the misinformation? Why does the first mention of a 13-0 score, as far as we can tell, not appear until 1997?
To my mind this is not an issue of honesty, because Laver is as honest a champion as the sport has had. I just think it's about memory, and the building of legends. Somehow the 8-0 result grew in the telling to become a 13-0 skunking in which Laver did not even win a set (something we all agree did not happen). Once that legend appeared, those who were there could theoretically have corrected the misinformation -- but after the passage of decades they would not necessarily remember clearly whether it was 8 or 13. For the numbers to be confused would be quite easy, because there were other similar numbers that applied to those tours: for example, as Urban points out, Laver played 13 matches against Rosewall in this tour.