Two of her five RG losses happened due to sickness. She had the flu in 2002 (really, she was probably equal to Serena and Capriati as favorite for the French that year) and then mono in 2004 when she was attempting to defend the title. Still, before that first retirement, she won half of the French Opens she contested. She had a very short career, but it's an incredibly fruitful one. You can consider Monica's longevity more impressive, sure. But considering Justine's career was really just about two-thirds of Monica's in terms length, I can only choose Monica if her stats were comparably greater, and they're not.The player whose career is perhaps craziest on clay is Henin.
Four French titles, we know, and three in a row from 2005-2007, but she won 'just' 5 Tier I titles on clay: Charleston twice, Berlin three times.
But then look at other details: 2002 French Open (a year before she won her first slam, but she was a top 5 player) she lost in the first round to Aniko Kapros, who peaked at #44, and in 2004, as defending champion, she lost in the second round to Tathiana Garbin, who peaked at #22.
In 2002, 2003, and 2004, her other clay losses were all to title contenders (Venus at Amelia Island, Dokic in Hamburg, Serena in Rome, Dementieva at Amelia Island, Mauresmo at Amelia Island).
She went undefeated on clay in 2005, and then in 2006 had clay losses to Petrova and Schnyder (players who crop up in Serena's list of clay losses), in 2007 a loss to Kuznetsova, and in 2008 a loss to Safina. In her 2010 comeback year, she had losses to Kanepi, Rezai, and Stosur.
It's too short a career to extrapolate really broad trends, and when she was really in the swing of things (2005-2008) she was only losing to title contenders and top clay threats. But there are some head-scratchers in that list.
I'm inclined to slot Monica Seles ahead of her on the list of clay greatness.
Monica won 14 clay titles, Justine won 13. Monica's winning percentage at the French is over 1% less than Justine's. And let's not forget. There's that one extra slam. I understand there are lots of circumstances to consider here but here's where we're at.
And if we want to count Justine's effectiveness, from 2003 to 2007 (her peak years), she contested 16 clay tournaments, she won 10. She reached at least the SF of ALL except the 2004 French Open.
As far as I'm concerned, Justine is the best cc player of all time.