Just for clarification.
The spot price and the future/forward price must be dictated by arbitrage relationships as I'm sure you know. Basically just 4 numbers spot(1+r)=fwd(1+q) - so the money you can make by being in cash bad better be the same as being in widgets. That of course assumes that there's no friction and that widgts are borrowable/lendable.
If there is a decent degree of borrowability/lendability of the asset then if the actual price in the future doesn't turn out to be well predicted by the spot price then it mainly means that the spot price isn't a good predictor of the future (or interest rates/commodity financing isn't)
FWIW the Dornbusch thing is a little sketchy too in my view.