LOL, never played UFC3 but I got your point, from what I expected UFC wanted to give either Romero or Rockhold the belt so that they could make up a Whittaker vs. The Champ #2 right after, but since Romero was overweight that kinda undermined the idea.
Still, Whittaker vs. Romero #2 is right now the fair way to go, let Weidman fight someone easier to pick up momentum, then someone in the hard tier (Yoel/Jacare/Whittaker/Rockhold, as long as not the champ), succeeding at both would make him belt material, pretty likely fighting against another one of that hard tier.
About the losses, I'm not sure if we're on the same page.. There clearly is a difference between losing to someone and being KTFO by three someones in a row. Gastelum although a talented fighter was indeed making his debut on an upper division, it was quite the least we expected from Weidman.