Originally Posted by Blizzard Entertainment
How will Ranks work in Standard and Wild?
When Standard format arrives, your current rank will be “split” and applied to both Standard and Wild in Ranked play. For example, if you are Rank 5 when formats arrive, you will be Rank 5 in Standard and Rank 5 in Wild.
Afterwards, you'll have a separate rank and match making rating for each format, so you can earn ranks and hit Legend in both Wild and Standard individually. You’ll only collect ranked rewards at the end of the season based on the highest rank you attained in one format or the other, but not both. Regardless of which format you earned your rewards in, end of season bonuses will be comprised of cards that are usable in Standard format.
Note that you’ll have one match making rating that is shared between both Standard and Wild formats when playing in Casual.