Batman V Superman: Dawn of Justice producer Charles Roven talked in some length about the selection of Ben Affleck as Bruce Wayne/Batman as part of The Hollywood Reporter's The Hollywood Masters series of interviews with influential filmmakers for students at Loyola Marymount University School of Film and Television.
Roven revealed one of the most important reasons why Affleck was their first choose and the "first guy we went to" was his age and compared to Henry Cavill’s Superman.
"We knew that we wanted a very mature Batman, because we wanted to juxtapose him with this very young Superman," explained Roven. "So we wanted a guy who was tougher, rugged, who had signs of life, who had lived a hard life, and we wanted the guy to have chops, for sure."
"We also wanted a guy with big stature," Roven continued. "Ben is 6' 4". Henry [Cavill] is 6'1". We wanted Batman to tower over Superman. Not hugely, not like a basketball player. Superman needed to 'look up' to Batman. We wanted that dynamic, and Ben could do that, easily."
Responding to the question of whether Affleck hesitated on taking the role, Roven replied: "No, I wouldn't say he hesitated. I think that what he did do was that he made sure that he understood what Zack [Snyder] was looking for."
Roven explained that Affleck wanted to know how Snyder planned to differentiate between Batman and Bruce Wayne, and apparently Dawn of Justice will mark a "completely different" iteration of that dynamic.
"He's much more of a social animal in the Bruce Wayne incarnation, but he's also an extremely rough guy in the Batman incarnation — very, very, very rough," Roven explained.