That’s always the question. How much is the car, how much is the driver?
Decades of watching the sport leads me to believe that driver skills are important, but matter mostly at the margin. (Unless we’re talking about drivers who buy their way into the sport.) Whereas the difference in cars - even on the same team - is determinative.
Driver ego and experience also plays a part. Specifically, as drivers get long in the tooth, they seem to be much more demanding of a specific setup and much less flexible in terms of accepting a car that doesn’t “feel” the way they like. (Michael Schumacher famously drove a setup that was so unique that it was almost undrivable to others.)
The only drivers I can think of who were so talented that they could elevate their cars beyond their capabilities on a routine basis were Senna and Schumacher. (Maybe Lauda as well.) However, it’s worth remembering that the cars were much less advanced in their era, which allowed driver skills to shine through.
With all of this as background, I believe that a big part of the reason that Hamilton was/is struggling this year is that something with his setup caused his car to “porpoise” on the straights to a much greater extent than Russell’s setup. And from the quotes I saw early on, the Mercedes brain trust was simply baffled by it.
I suspect that Hamilton’s car will improve as the season goes on and he will get back to something close to his usual form.