This is the break down as best as I can.
Serena, Navratilova, Graf, Court, Evert CLEARLY Top 5 in the Open Era. That is the Top tier, way above Maria.
Henin, Seles, Venus, King, the next tier. All clearly over Maria too of course.
Hingis and Goolagong in their own tier after that somewhere. Both clearly over Maria too.
So not a chance she is Top 11. I already named 11 players far over her. This is where it starts to get interesting. What is the order of Sharapova, Clijsters, Davenport, Austin, Mandlikova, Sanchez Vicario. Considering Davenport's 4 Year End #1s when Sharapova could not manage even 1, and the doping asterisk no matter how many, and I rate Davenport over her even with the 2 extra slams. Clijsters has a more impressive career in almost every aspect except for 1 less slam, no Career Slam (which isn't a big deal, especialy in womens game), and adding on the doping asterisk I likely have her over Sharapova too.
Sanchez Vicario probably goes behind her. Austin and Mandlikova probably behind her too. For now she probably barely makes Top 15, but I am being generous in being super leanient by almost ignoring her being a doper, and other factors. Many others probably have her 16-20, but I will be kind and say she barely makes Top 15.