Dan and BobbyOne,
Let's try to be logical about the head to head of Rosewall against Hoad on clay. Dan, what is your head to head records on clay of the two and what is your head to head records in total?
BobbyOne, same questions.
The reason I ask this is because we have to see if the percentage that either one of you have of the two playing on clay is reasonable or not.
Part of the problem is ignorance; we do not know the surfaces for every score we have.
Here is a partial list of Hoad wins over Rosewall:
1952 Australian Hardcourt Final (shale clay)
1953 Australian Hardcourt Semifinal (shale clay)
Hoad and Rosewall skipped the 1955 clay season preparing for the Davis Cup, and Hoad won many clay events in 1956 while Rosewall was in Australia preparing for Wimbledon on grass.
1957 European tour: Hoad won tour on red shale clay against Rosewall (6 to 3?) (8 to 4?)
1957 The Hague: Hoad defeated Rosewall in marathon five set final on red shale, Segura in semi-final.
1957 Cairo: Hoad defeated Rosewall on clay in marathon five sets
1957 South Africa: Hoad won tour, but surfaces are unknown.
1959 Roland Garros: Hoad wins third place against Rosewall
1960 Geneva: Hoad defeats Rosewall in final
1960 Tokyo: Hoad defeats Rosewall in Japanese Pro final on clay
1962 Hoad wins Italian tour on clay, Hoad/Rosewall matches unknown
These are the known Hoad wins.
For Rosewall over Hoad;
1958 Roland Garros final
1960 Roland Garros final
1962 Geneva final
1963 Poertschach, Austria (Bobby, did you see it? Was it on clay?)
1963 and 1964 Cannes, Palais des Sports, possibly indoor, not clay
Looks like a probable edge for Hoad, although any clay matches after 1964 came after Hoad lost his large right toe to surgery, and was less mobile.