I'm not cherry picking I'm just talking about the recent years and I'm completely aware that the economic situation is due in large part to low oil prices. There was no problem being popular when high oil prices and an open market meant steadily increasing standard of living.
What I'm discussing is how
hard it is for any politician to be popular in the face of rapidly decreasing purchasing power and living standard such as when there is a budget deficit and inflation. So why isn't Putins popularity decreasing when the economy is? Is it because the people saw what he did in 2008-2014 and trust he can bring that back? Makes sense, but a diverse media would question that idea. It wouldn't be enough in any country with a working media and opposition. Leaders in working democracies don't have that high approval ratings even in good times.
The last couple of years have seen large inflation, and also stagnated salaries/pensions. This is a very recent phenomenon and started with falling oil prices and was worsened by the Crimea sanctions.
You could argue that discussing 2013-16 is cherry picking but those 3 years are pretty special -- they are the most recent 3!
With the sanctions in place 7+ percent inflation and oil prices looking to stay low for a long time, spending 5-6% on the military while the public can buy less every month for their salaries is only sustainable in one single way - make a story that the nation is in a conflict with an external enemy. That it's "us against them". It's simple nationalism and it has always worked. To support that story you cannot have an alternative narrative either so you must effectively control media and ensure there is no working opposition. This is exactly what the rest of the world believe has happened, which is why everyone is worried. It's becaus we fear that given enough time - the people of Ru wouldn't actually know they don't like Putin because there is no media that gives them any reason not to!
The point isn't that Putin is mismanaging the economy directly - it's that he is isolating Russia economically e.g by the Crimea story which will hurt the economy over time.
The same would happen in the US if Mr Trump was elected, but the difference there would be that media would eat him alive after that (e.g alienating Mexico or the entire Muslim world) and the opposition would win in a landslide come the next election.