Great insight and example, yeah that's how things were before 1989.
Your example with Navratilova reminded me of one issue we discussed here in the past: top Czech players, Petra included, sometimes struggle with their compatriots despite being the clear favourite to win the match. For example Petra's straight-set loss to Hradecka in Madrid and the loss to the same player in the Extraliga finals (despite being ranked much higher) or the struggle with BZS at the 2011 Paris Indoors (Petra had to save a matchpoint).
Now look at this funny past example which concerns Martina (take it as an off-season speculation on tennis history
In 1983, Hana Mandlíková defeated Martina Navratilova in three sets in the final at Oakland, California, ending Navratilova's 54 match winning streak
, two short of tying the record held by Evert at the time. Navratilova then embarked on a 74 match winning streak
, a record that still stands.
So, if Navratilova was not defeated by a fellow Czech player (product of the same system), she could have been on a 128-match winning streak!
To make it even more amazing, who did snap Martina's 74-match winning streak in 1984? Yes, another fellow Czech player, Helena Suková (and denied Martina from calendar grand slam)!
Considering that in 1984 Martina had a 82-2 record, if it were not for fellow Czechs Hana and Helena, she could have been on sth like a 150, 160 or even 170-match winning streak
Conclusion: Petra better learn from the Martina example and watch out when playing fellow Czech girls, they have no respect and can deny you from a calendar grand slam or snap the best winning streak ever