Opponent FG% is a good thing to examine but why not look within 6ft if you're looking at that?
Also, I think the biggest problem with Lee is not so much his post defense but his inability to cover the pick and roll, which you can see in this video (which is, incidentally, a couple years old and doesn't focus on Lee specifically).
https://www.youtube.com/watch?v=NCUmqb9L7_4
of note: getting taken off the dribble by renown dribble artist Omer Asik at the 20 second mark.
Do you really consider that sort of anecdotal video to be any more useful than all the anecdotal highlight reels one can always find that make "player X" look like a superstar?
Just as even the most clumsy D-Leaguer will occasionally have that perfectly timed play that has him exploding to the hoop, slamming it home like MJ, even the best defenders get caught leaning or out of position or whatever, resulting in a play that makes them look like a matador.
Aside from the anecdotal nature of it, how relevant is it if it is from a "couple of years old"? I've already shown how the team around Lee changed and how his defensive numbers changed with that since that video was made.
I've given you numbers that indicate that, statistically, the teams and units that Lee played on for the Warriors more recently have posted very good defensive numbers. If Lee were truly as easy to exploit as this video would suggest, don't you think that teams would have been all over that?