" Age was also factored in, while if a driver was coming back to the sport after three or more seasons out of F1, that was also considered. "
Funny, that. We wouldn't want Nico Rosberg at #2 would we?
I have many issues with this, not least whether all sessions are included (Mercedes times in Q1 since 2014 mean nothing - similarly if a low ranking car makes it to Q3 they often will risk less, knowing they're going to be P10 regardless), and particularly whether wet sessions are included. That adds a lot of random variability to the data.
More profoundly problematic is the fundamental difference between qualifying now and in the 1980s. It was less important then as overtaking was generally easier, and qualifying engines and tyres created much bigger gaps between cars and drivers, plus there was the Friday - Saturday problem to overcome with different track conditions, and much worse reliability; then we have the situation in the current period of drivers hurting their ultimate pace with a harder race-oriented tyre selection in Q2.
Having said all that, Kovalainen was generally closer to Hamilton in qualifying than we probably remember.