Reason why #TheMiz was moved to #Raw
The reason The Miz was moved to Monday Night Raw is, #WWE felt like he had plateaued on the blue brand.
The original plan was to have Miz do a "long con" feud with current #SMACKDOWNLive General Manager Daniel Bryan, eventually leading to a match somewhere down the line. Miz was even told to do Bryan's moves during his matches, to play up the storyline. When it became clear that WWE doctors were not going to clear Bryan to wrestle, plans were altered drastically that So much so that the purposed Undertaker vs. John Cena match was nixed and the the Deadman was moved to Raw, to feud with Roman Reigns. (who was originally supposed to face Brock Lesnar for the Universal Championship, before Goldberg agreed to a contract)
This led to the mixed tag match at Wrestlemania. WWE was hoping Daniel would be healthy enough to have one final match with Miz in Orlando, but this was, unfortunately, not the case.