Winger
It's funny to say Orlando City needs to improve at winger, because the club definitely knows this. Orlando signed four wingers last season (if you include the injured Gaston Gonzalez) but never found a true partner for Facundo Torres on the opposite side.
To win MLS Cup or compete for the Supporters' Shield, Orlando needs more depth of quality in attack and more tertiary creators and goal scorers. That starts on the wing. One of the signings from this past season, be it Gonzalez, Ivan Angulo, or somebody else needs to step up and be a legitimate starter for this team.