Look-wise, he is a perfect mix of Sean Penn and Adrian Brody. It's uncanny.
Talent-wise, he's a celebrated character actor, and Academy-Award-nominated. The man is a chameleon. He could take this character any number of directions and still land on something memorable. And you'd better believe you wouldn't recognize him.
He's older than Affleck, but not by so much that the two characters couldn't have a credible long-term relationship and history.
He brings the looks and the pedigree. In my opinion, it's a perfect match post-Ledger.