I don't typically equate being one of the worst of the best with being 'ok' or 'average' but this conversation has reached 'middling'.
I just took it for granted that when we were evaluating three point shooters we were comparing them to other three point shooters. That would explain why we don't typically see threads about how Bass is an above average rebounder or Sully is a good shot blocker, both of which are probably true if you compare them to the league as a whole. Also, I expected to see something a little more exciting than "Lowry doesn't hit an overly high amount of his threes but he sure takes a lot of them" when you were chiding me for not doing enough research before I commented.'
Perhaps these numbers will prove more enlightening --
Going back to the comparison I made before between Kyle Lowry and Paul Millsap . . . .
According to Basketball-Reference, Kyle Lowry was assisted last year on 57.6% of his three point baskets. That was significantly lower than the previous two years, when his three point percentage was better.
Kyle Lowry shot only 14.8% of his three pointers from the corner, and since the 2010-2011 season has taken between 9% and 15% of his three pointers from the corner. His percentage on corner threes has never been much better than his overall three point percentage. Between 30% and 45% of Lowry's attempts since he became a full time starter have been from deep.
Paul Millsap, by comparison, was assisted on 94.8% of his three point baskets last year, and for his career has been assisted on 95% of his three point baskets. Between 20% and 25% of his three point attempts are from the corner, where he shoots a very good percentage -- 42.1% for his career. For the last two years since becoming a regular three point shooter, about 20% of Millsap's attempts have been three pointers.
From all of that, you can tell that Millsap is probably a better spot up shooter from deep, especially from the corner, than Lowry. But Lowry takes many more of them, and the degree of difficulty on those shots is higher. While taking unassisted three pointers is typically a bad proposition -- and therefore a poor decision -- Lowry probably has to take a good number of those because his team has put relatively few quality spot-up shooters around him.
Now I don't know how without taking ages to do it, but if I did, I'd look up to see how Lowry compares to all players in the league with a similar percentage of unassisted, non-corner three pointers. That might give a better sense of what kind of shooter he is. Working in his percentages from the last couple of years to give a larger sample size would also help.