I find having Goolagong-Cawley even in the poll is terrible, sorry. She is a great player who played in a super tough decade with Navratilova, Evert, Court, King, and Wade. She still managed 7 slams vs that field, and atleast 2 of her 4 Aussies were legit as she bageled Evert in the 3rd set to win one, and trounced a young Navratilova in the final of another with Navratilova knocking out Court to get here. Her 2 Wimbledon were most impressive fashion, straight setting King and Court back to back to win one, and well past her prime knocking off a prime Austin and a prime Evert in big upsets to win the second. Her never winning the U.S Open is a travesty and a sign how tough the field was that decade, combined with some bad luck. She put on some scintillating performances there, an amazing final with Court in 73, a great performance to knock off Evert in the semis then a thrilling final with King in 74, a great final on clay with Evert in 75. She really was unlucky to not win atleast 1 of those if not more.
Plus she was the true #1 for the year 1971 anyway for all practical purposes as well when she won both the French and Wimbledon events.
Yes she was considered a bigtime underachiever still given her talent, but I think that causes some to diminish what she was, somewhat like Safin for some people (although Safin is nowhere near as accomplished as her obviously). Even based entirely on what she was, not on what she could or should have been, she still is the cream of the people on this poll.