Ayer has gotten plenty of strong performances out of his past films. Hell, Fury alone has at least three.
Ayer wrote a bad script. I think most of us can agree on that. But I keep seeing this idea being perpetuated that just because fans were underwhelmed with Leto's Joker, it means Ayer cannot control his actors or channel good performances out of them. That is categorically false.
In fact, it's his work with actors that I'm sure excited most of us about his involvement in the film. And honestly, if this is the best he could do with Leto's performance, then that's troubling. I really don't see some magical scenario where Leto delivers a great Joker. A better script would yield better dialogue, but you could swap in Ledger's dialogue from TDK and I'd still imagine a **** performance. The characterization is the biggest issue, not just the words he's saying.
Besides, who's to say Affleck didn't love what Ayer and Leto did with the character? In fact, I'm fairly certain he said that he did.
A lot of assumptions being made here. The truth of the matter is we do not know the true extent of Affleck's Batman geekdom. What evidence is there to suggest that he understands the source material and depth of these characters more than Ayer, who actually researched Suicide Squad comics when writing the script?
Remember. Affleck was on board with a Batman who didn't seem to care about killing criminals, and who plotted the assassination of Superman.