Moxie, isn't dominance an important factor in greatness? I think part of the original author's argument is that it is a central factor; meaning, a player's greatness is significantly determined by their dominance over their peers and era. To call it a "testosterone driven notion" kind of undermines the entire competitive venture of professional sports altogether.
This discussion reminds me of some previous discussions around players like Lendl and Murray, who having losing records in Slam finals: 8-11 for Lendl, 3-8 for Murray. How do those lost finals impact a player's legacy? If we compare Murray and Wawrinka, who was 3-1, is Andy a lesser player for losing so many more finals?
I'd personally say no, but the opposite: the fact that he reached 11 finals is rather striking. I've mentioned this before, but it puts him in a different group of players than Stan:
Most Grand Slam Finals
30 - Federer
25 - Nadal
24 - Djokovic
19 - Lendl
18 - Sampras
16 - Borg
15 - Connors, Agassi
11 - McEnroe, Wilander, Becker, Edberg, Murray
8 - Rosewall, Vilas
7 - Newcombe, Courier
6 - Laver
5 - Kodes, Ashe, Nastase, Roddick
4 - Chang, Ivanisevic, Rafter, Hewitt, Safin, Wawrinka
Now obviously a lot of other factors have to be included to assess a player's overall greatness (or dominance), but this list tells us a lot about Murray and Wawrinka, and how they compare to other players in terms of reaching the final of a Slam. I've said this before but Andy Murray is probably the one player whose career resume was most negatively impacted by who his peers with (with honorable mention going to the other Andy, Mr Roddick). If Murray had played in almost any other era he probably would have won twice as many Slams, plus or minus a Slam or two, which is why I consider him just behind the Becker-Edberg-Wilander trio and ahead of Vilas-Courier-Nastase-Ashe.
Similarly, but to a lesser extent, with Roddick, whose 1-4 record at Slams is entirely because of Roger Federer. Not only did he lose 4 Slam finals to Roger, but he lost 3 SF and 1 QF to Roger, going 0-8 in later round matches to Federer. If he had played in a different era or Roger had chosen a different career, chances are Roddick would be in the 3-5 Slam title range.
Of course we all have to deal with the hand we're delt, and we can only judge players by what they accomplished - not what they "woulda" or "coulda" if only things had been different. But looking beyond just Slam titles at things like Slam finals - and various streaks and other angles - gives us a deeper sense of a player. Andy Murray is more than just a 3 Slam player; Andy Roddick is more than just a 1 Slam player. Etc.