You're also saying Rosberg us more consistent and made less errors. He made errors to stop him qualifying close to Lewis in the early races. He made an error in qualifying at Monaco and he made an error leaving the track in Canada. That's quite a lot.
Lewis made an error in Austria quali and made a wrong decision in Silverstone quali. I'd say far more errors to Rosberg, he's just been lucky in that his worst errors benefitted him and hampered Lewis
Rosberg has made less errors in quali than hamilton has. He botched up monaco and lewis didn't get a final run in because he wasn't smart enough to set a pole lap up front like nico did. Even if rosberg got 2nd and hamilton got pole in monaco, he'd still be more consistent because of hamilton's last two qualifying sessions, albeit very marginally. So it'd be either 1 mistake for nico to 2 for lewis, or 0 for nico and still 2 for lewis if rosberg didn't make a mistake in monaco. This season may come down to such small margins.
Ok geet, Nico is a better qualifier than Lewis and has done better, so why is he only 4 points ahead despite a dnf from first for Lewis
Ah, that must mean Lewis is way better on Sundays, the one time Nico qualified in 4th vs the time Lewis qualified in 9th, who drove better recovery drive to the front?
Good thing for Nico is that they now give a trophy for Saturdays, so he won't mind half the points Lewis gets on Sundays when they both finish 
Now you're not even on track because you don't have an answer to the fact that nico has been the more consistent qualifier than hamilton this season.
There is a big difference between consistency and performance geet
You say Nico is more consistent than Lewis in quali because he has a better average position. This however doesn't mean Nico has made less mistakes as he hasn't, it just means Lewis' mistakes have had more costly consequences - this is complete luck
Therefore Nico is less consistent in quali as he has made more mistakes but he has been lucky enough to have less costly mistakes therefore has better results
Nico has been less consistent than Lewis in the context you are trying to sell, this year and last year, unless ofcourse you care to list the number of mistakes made by both or unless mnm is willing to come out of hiding while Seb is still getting a spanking from his teammate