Martina will always be underrated and under-accomplished.
To put a broader perspective on Martina: another problem with her is that since her early childhood she basically pursued two completely different sports - the first one professionally, the other one as a past-time activity.
When she was 3, they moved from Slovakia - where she started hitting the ball as a 2-year-old kid - to a little rural town in east Czech Rep. where she developed her tennis skills AND fell in love with horse-riding. This continued in Switzerland.
I read couple of Czech or English interviews with her and I really think that this girl loves horse-riding as much as playing tennis.
Tennis was basically 'imposed' on her by her ambitious mother, while horse-riding was her free choice.
That's why I think she had no problem to retire at just 22 on a huge pile of cash. I've read somewhere that today she rides her horses four times a week and even spent a month in Portugal at some equestrian competition.
BTW, it's common knowledge that she fell off a horse before the 1997 RG final.
So overall I think that tennis was not everything for this girl and that's why she underachieved and had no problem staying four years away from the tour before her relatively sucessful comeback.