Not McVay's fault that the league rules favor the pass and the emphasis on the running game (and running backs, and their salaries) hs been diminished.
Not Gurley's fault that he was overpaid - he was a pariah on the market both before and after his big contract.
True, RB's get banged up and most have to retire after about four years. The way today's game is played, they are for the most part replaceable. The outliers, though, the Derreck Henry's, continue to get big bucks. Henry (had to look it up) is pulling $14 mil this year. That's wideout money.
Melvin Gordon is a real good player - but not an outlier. He doesn't bring Henry value to a team. So, he gets paid less. Finding a scapegoat doesn't change that.