Gibraltar's strong but he's not a rush down character so he doesn't blend well with most teams. When using him I also prefer to avoid buildings and over hanging cover since its hard to use his abilities there. The problem seems to be that characters like Caustic and Gibraltar are highly dependent on their abilities while Wraith can get by with just a gun and her small hit box.
I still feel the solution is to shorten the delay on every legend's tactical (except Pathfinder and Wattson). Can't say that I know anything about balancing a game but the damage reduction buff has little noticeable effect and I want to respect their decision to have different sized characters.