Rosewall won 4 slams and 2 WCT finals in the open era. He also reached 4 other finals as well as winning about 35 other tournaments, all this after turning 33. He had a YE ranking of #12 in 1977 at the age of 43. Laver won his last slam after just turning 31 in 1969 and never reached a slam final after that.
He did not play that many.
I would never want to pit these mates against each other (except on a tennis court). But your post gave me the feel you were demeaning Laver in comparison to Rosewall. They had different strengths and much different paths or trajectories. Both were unique - Rosewall uniquely young and old champion; Laver uniquely dazzling game and five-year dominance.
Between 1970-74, by which time he was now 36, Rocket played a TOTAL of six slams. In some cases choice, in some cases he prohibited from participation or had to uphold a vital labor boycott. Wimby and USO in '70; AO and Wimby in '71; USO in '72 and '73; zero in '74. In the Open Era, Laver won about 20 Masters 1000 equivalent or better titles, plus arguable Majors at Tennis Champions Classic and the true world clay court championship of 1971 - The
Internazionali d' Italia. Laver won approximately 70 tournaments in the Open era. Laver's overall record compares very favorably with Rosewall, IMO, except for the important point that Ken was four years older. In the Open era, Ken won five or six M 1000 - like tournaments, not including the Slam and slam-like tournaments you cite. Kenny turned 35 at the end of the 1969 season. He then had five Slams (I count the WCT Finals). That exceeds Federer (3) and Nadal (2). It is about equal to Djokovic (4 plus one undefeated YEC). He trails only Tilden, at seven after 35 (US Nat'l, Wimbledon, two WCS, two US Pro, French Pro). Bill also has the finals - at age 42, he lost the Wembley final to Vines, at 6-1 6-3 5-7 3-6 6-3. Let's say Djokovic is down but not out. The over-35 GOATs will be Rosewall, Tilden and Djokovic, not in any particular order. A little behind them will be Segura, Gonzalez, Federer, Nadal.
For the 30-35 cohort, you have Djokovic first, then Tilden and then several: Laver, Gonzalez, Rosewall, Agassi, Nadal, Federer, and a whole bunch more (Segura, Kramer, Johnston, Drobny, Borotra, Ashe, Gimeno, Emerson, Perry, Cochet, Wawrinka, et al.)
Laver at age 33 was World No. 1. He was still No. 1 at 33 and five months, at the end of 1971, in the opinion of many, myself included, and also including TB and UTS. He has been eclipsed as oldest No. 1 by Djokovic, and, maybe, Tilden in 1930-31 (it is debatable), or, even Federer in 2017 maybe (I am talking year-end No. 1). But the only way to make Laver look burned out in his mid 30s is by comparing him w Djokovic, or maybe Rosewall.
But, really, I never like putting Laver and Rosewall against each other. Their trajectories were so different. Rosewall was a prodigy, a world champion at age 18. He spent a lot of years somewhat underrated but very successful and steady, until he took over the throne from the retired Richard Gonzalez in 1962. Kenny was then 27 years old, thereabouts. He was No. 1 perhaps three years until overtaken by Laver. Laver dazzled and Kenny kept on as always. And he did outlast Laver. It is a very singular career. To be a Slam champ in 1953 and in 1972. It is a longer span than Tilden (barely), and beats the Big Three by two or three years or so.
Laver was not a prodigy. He did not get his game together until about age 23. Even when he took over as No. 1 in 1965, he was not yet complete - that came the following season. And then, for those who like five year peaks, Laver had about the greatest ever, starting maybe late 1965 and through mid-1971. He had two Grand Slams in that time (1967 - US Pro, Wembley, French Pro, Wimbledon Pro; and 1969 of course). Between the start of 1966 and the 1970 Tennis Champions Classic, Laver won 13 of 16 majors he played (finishing runnerup at 1966 French Pro, 1968 French Open, and losing in the 4th Rd at '68 USO)
Having finished 1971 No. 1, at age 33, he did start to drop off. But he was still winning elite titles.
The Laver-Rosewall competition was on the court. I like to think of them in harmony now. Rosewall, the longest effective career of any player, and the most Major titles of any player (27 by my count). Laver very possibly the most dynamic game ever seen. Three Grand Slams. The most tournament titles of any player and the most elite (non-Major) titles of any player with the probable exception of Djokovic. When you add non-Slam elite titles to Kenny's haul of majors, he is not so far behind. Laver has about 46 elite titles (non-Slam), and Rosewall about 36. But Rosewall has more Majors, 27 to 23. And Laver is tops in titles by a lot, but Rosewall is third.
I would never want to pit these two against each other. They were both the best.