#3 Bray Wyatt

How a superstar goes from walking into WrestleMania 33 with the WWE title around his waist to mid-card fodder on raw is beyond comprehension, but that's exactly what happened to Bray Wyatt over the course of 2017. Of course, losing the title to Orton at WrestleMania 33 did help him either, but one has to wonder why this was done.
Furthermore, one has to wonder why Bray Wyatt was even moved to Monday Night Raw after WrestleMania 33 if they weren't going to utilize his talents either. Sure, Wyatt and Balor took part in a decent mid-card feud towards the end of the year, but the momentum was stalled when Wyatt contracted a viral infection and was unable to compete.
With that all in mind, it seems like WWE has no real plans for Bray Wyatt in the near future and he is definitely one of the biggest superstars WWE gave up on in 2017. In the end, maybe things could get better and maybe this is just pessimism on the writers part, but things aren't looking very good right now with the position he currently finds himself in.