Imo there was tougher opposition in the Borg era.

He only played for 9 seasons and entered the Australian just once. Fair comment on the US open wins but Borg was up against Connors and Mcenroe who were better on that surface eg like Fed with the French because of Nadal. He got to 4 finals.

11 slams and 5 finals in 8 seasons when he only played three of them (didn't enter the French one year when at his peak) and walked away aged 25.

That's some going