Indeed, there are many different meanings of the word raw - the COD lists eight - but the first /principal meaning, I would think, refers to uncooked food.
I suppose a phrase like ' training the rawest recruits' might be considered common.
Digressing slightly, another 'problem' with these words is pronouncing them as two syllables without turning the 'w' into an 'r'!
Not easy for a native speaker - a task of herculean magnitude for many Asians!!