Monica ascended the rankings faster than anyone before or since.
Monica never played any ITF events. She played 3 WTA events as an amateur when she was 14 in 1988. At 15, she turned pro and played 10 events that year: Her 3rd pro event (6th career) she made the semis of the French Open losing to Steffi Graf. Her 4th pro event (7th career) was Wimbledon where she lost in the 4th round again to Graf: 5th pro event (8th career), she lost in the 4th round of the US Open to Chris Evert.
She ended the year with a win/loss record of 33/8. Her only losses that year were to Evert, Graf, Navritolova, Novotna & Ferandez.
The following year (1990) Monica won her first GS title at RG in only her 22nd career tournament and her 4th GS. She followed it up with the classic 5 set win over Sabatini in the YEC. She would win her second GS title at the 1991 AO and become number 1 after the following tournament, the 30th of her career.
Monica was a true phenomenon and I don’t see anyone ever duplicating her precocious ascent to the top.