I think you're a bit late if you wanna play that scenario. It's been years since forecast about global growth are downgraded, little by little.
I am not saying that we're not going to be bearish commodities. But it ain't gonna be a surprise. I'd rather be ready to buy in case a war or a black swan would suddenly explode from nowhere.
My 0,2 cents.
I advise strong filtering,
As someone said on this forum,
And he must not be the first to say so:
Extra Returns if and only if extra circumstances.