Most 6'11" guys are really 6'9". You'd expect more of them than those 7' or taller.
But if there are also more of them than those listed at 6'10", who are really 6'8", then I'd expect that that's the height for which there is a premium in simply being tall: less talented b-ball players can make it if they are at least good PF or C height.
Likewise, I'd expect there is a premium for those who are at least 6'5"--or 6'3"+ without shoes. If they're that tall they can win out over more talented shorter players who lack SG height and they are overrepresented among players that make it to the NBA compared to shorter guys.
To a lesser degree that probably happens at minimal PG and SF heights as well.