Can you get these offline? If so how?
The legend 42s were only available in pre-order bundles I believe. The current player 42 cards are available through Team Affinity. Not sure if/when the legend 42 cards will be available again outside of the market, but have to assume it's coming.
I'd guess the legends 42 will be in a pack hidden in the 2nd inning conquest, 3rd inning at the latest. If they release them too late they'll be irrelevant because better cards will already be out.