When he's relevant as a singles guy. At the moment he is kind of stuck in one location. Most of the Shield is focused on Reigns and have been for a couple of months now, and before that it was on the tag team mainly since those two were the guys getting ring time. It's weird because Ambrose at the start was the guy getting main focused but sometime over the summer they slowly started moving it more towards the tag team and then Reigns. Like Shadow said, let him establish himself in the midcard first, create something the fans will connect with, this can lower the risk of some form of lashing back effect once he gets a main event run. Most of the main eventers that stick are the once that get to simmer in the midcard first and build an organic relationship with the crowds.
Plus as others said, I see him more as an upper midcard heel than a main event one. A Pillman, Roberts or Piper, the guys he's compared to the most. He'll be in the dance, but not leading so to speak.
