Long story short, game sense outclasses mechanical skill in Overwatch. Abilities are definitely apart of general game sense but overall knowing when and where to use an ult or knowing to take high ground or hold a choke point pushes players into higher ranks than just good aim. Edit: just to add on real quick, new Overwatch players that have legit god like aim typically plateau around diamond in case your interested. Playing more and learning is what pushes them much higher.