Obviously, the rarest and best rewards are, well, fairly unlikely, but the crates at least allow you to reroll items that you already own at the moment. (The designers are looking into other ways to make “getting stuff you already have” feel like less of a letdown.) We can’t tell you if this will make you any less angry about lootboxes, but at least disclosing the odds is pretty decidedly a step in the right direction.
Source: Official Site via Kotaku; thanks to Pepperzine for the tip!