How was he "bested" by Heath Ledger? If Ledger hadn't died shortly after the movie...
He actually died while Dark Knight
was still in production. I when Ledger died Warner put out a statement he pretty much finished filming his role.
...everyone would have said he was good, and nobody would have cared anymore. It's the River Phoenix Syndrome. Make a decent movie, die, and suddenly you're this Legendary actor.
Meh, his accolades for the movie
were deserved regardless. His portrayal of The Joker in the movie was essentially how I imagined him from the comics. Nicholson's Joker was ridiculously comic and just showed the character as a lunatic madman. No depth, no substance, just a white-faced clown in a purple suit.
Not saying Nicholson's role was bad, not by any means. But he certainly didn't get any inspiration from the comic-series Joker.