Ultimately, positioning means standing in a way such that it decreases the chance of your opponent hitting shots that are physically/technically difficult for you to hit back.Excellent post, including this point.
Under 4.5, pretty strokes have zero correlation to score, as evidenced by this bagel incident.
Knowing where to stand is one of the least obvious things to a beginner player.
I still have no idea where to stand.
e.g If you stand inside the baseline, it increases the chance of you receiving a shot that is physically and technically hard to hit back - a shot that lands deep near the baseline, not only because it's deep but because you have less time to react/prepare.
Most importantly, there's no universal way of where to stand. It always depends on 2 factors:
A) Your opponent
Examples of A:
If you notice, for some reason, your opponent can't hit forehand crosscourt (only dtl fh) then it's wise to stand a bit further to your left
If you notice your opponent always hit short balls, then it's wise to stand closer to the baseline
Examples of B:
If your reaction time is terrible, it's wise not to stay close to the baseline.
If your backhand sucks, it's wise to stay a bit further to the left.
And your goal is to find the balance between A and B.
At higher level, you can also see the difference in positioning between pros, Fed and Rafa are 2 prime examples. Both stand in a different way such that it's physically/technically/strategically easier for them to hit the ball back, thus optimizes their chance of winning.
Optimality is the true perfection.