Well people say Borg is a strong number 2. Not sure what more you want. When people say Nadal is the undisputed #1 it doesnt mean Borg is way behind, just that he clearly is behind and it is without real debate at this point, doesnt mean by a huge margin.
I think Rosewall is underrated and should atleast be rated up with Borg on clay, if not up with Nadal. It is truly sad alot of this forum actually thinks Federer is a better clay courter than Rosewall (what an epic joke that is).