The biggest tragedy of the DCEU may be the lost opportunities that could've truly challenged the Marvel Cinematic Universe. Ben Affleck's version of Batman may be the biggest loss. Not only did he bring brilliant creative energy to a very well-traveled character, but his Oscar-winning skills behind the camera promised an incredible stand-alone Caped Crusader film. Affleck left the role before that could happen, citing a need to focus on his health and personal issues, as well as dissatisfaction with the creative direction of the troubled franchise.
Source:https://www.cbr.com/robert-pattinson-good-batman-ben-affleck/