In the Borg/Connors/McEnroe era, the AO was not routinely played at all by the top players. Borg played it in '74 once when he was 18 (lost 3R on grass). Connors won it in '74, but lost in the final in '75. McEnroe never played it until 1983, when he lost in a SF on grass to Wilander there. He only played it once in his prime before making one more return to the AO late in his career, when he got defaulted in 1990:
http://www.youtube.com/watch?v=-52G_eaAni4
Lendl won 8 majors (FO, USO and 2 AO). During the late 1980's the AO had gained some traction and he played it several times and took 2 titles there. In the late 1970's-early 1980's and even before, during the earlier Rosewall/Laver years, the AO was not considered a "major" by the players, though the Australian Tennis Federation "campaigned" for such standing. Even
Australians didn't play it many years during the 1970's. Laver only played a few slams in the early 1970's and then there were no more slams played for him (complicated "Tour" commitments/contracts may have been a cause).
So, you can remove that as a "viable" Slam to be garnered by Borg and McEnroe. With Connors, he won it with a thin draw in '74 beating Phil Dent in the F and then lost a close final to Newcombe in '75. Yet, he never played it again after that during so many "prime" years.
Rod Laver was considered the "greatest" ever until Borg started racking up Slams. Then, it was Borg or Laver? Who is the greatest, with only perhaps Tilden, Budge, or Gonzalez also discussed some, but not much. So, Laver was the measuring stick and he had two GRAND SLAMS in 1962 and 1969. He won all 4 majors twice, with '69 being the most impressive since '62 was the Pre-Open era). Yet, remember he finished with 11 slams, while Roy Emerson had 12 GS titles (again pre-Open era, when you had "amateurs" and "Pros". Emerson was winning Slams against other amateurs and not the best players in the world). Many players and experts, including Arthur Ashe considered Borg the greatest ever by the time he won Wimbledon #5 in a row. He took GS title 11 at the 1981 FO and never played another major after the '81 US Open (he was 25 then).
So, there was talk of chasing two things: GS titles at the FO, W, and AO (he won 11 of those GS, and reached 4 USO finals). Had he won a USO along with W and the FO, he would have surely gone for "Laver's GS". Yet, he didn't. So, none of the top players played it.
Then Sampras came along. He had NO chance at the FO, so NO GS possible. He started racking up Wimbledons and US Opens and now AO titles too (2). So, lots of majors but no calendar "Grand Slam" was possible. Yet, he could pass Emerson and he did when he won his 13th Slam at Wimbledon, which was talked about a lot. THAT was when the shift occurred as far as "counting GS" totals to try and compare players ACROSS eras. He then went on to win his 14th at the US Open.
http://www.youtube.com/watch?v=fCL0KHenHXk
So, once Federer came along, the "measure" had become getting to 14 slams and passing that total. No one would say Emerson is better than Laver and Borg because he has 12. Yet, there is a new paradigm now, with TOTAL GS titles being a big, overall measure of who is the "greatest". So, yes, the "goalposts" have moved around a bit. Yet, a couple of things have been consistent,
big goals for all time greats such as Laver, Borg, Sampras, and Federer. Namely (1) trying to win the calendar Grand Slam (Laver in '69) or (2) racking up FO, Wimbledon, and US Open titles. That's basically how things played out for all these Greats over these different eras in terms of the last 50 years or so from 1960-2010. First Laver, then Borg, then Sampras, and now Federer. Each have been considered the "greatest" during their respective eras.