This is an intriguing discussion. I think that in the future more attention should be given to the ST/TO ratio. It seems to tell us something important about a players contribution. Clearly the value of a high steal total is diminished if a player's turnover total is even higher. Of course that player may be making huge contributions in other other areas such as assists and points.
I like your fascination with that stat, but I think steals is not necessarily an indication of defensive proficiency - there are great defenders who do not get a lot of steals, just like there are great defenders who don't block many shots, or grab lost of defensive rebounds. It is really hard to quantify defensive success - we know it when we see it, but ... And of course good defense depends a lot on 5 players not any individual. And a lot of steals are the result of cheating off your own player and surprising an unaware/inept offensive player.
And turnovers are really a negative offensive stat and generally correlate to assist number - PGs because they handle the ball so much and attempt more passes tend to have more turnovers than their teammates.
So ... while interesting - just not sure it necessarily tells any particular story.
There are various stat compilations that combine all recorded individual stats into a single number - made shots, missed shots, assists, steals, rebounds, turnovers - in an attempt to record a value for productivity while on the court.