It's not 9.6 anymore, it has descended to 7.3. That's still twice as high as the Rotten Tomatoes score, but that isn't too surprising because IMDB scores are, in my opinion, largely horse-shit.
There are two big factors that contribute to the difference. Let's look at a side by side demographics profile of the IMDB score on 23 March, 2016 and 1 April, 2016.
If anyone tells you there are objective standards, they're full of shit. This is a matter of personal taste. There are trends. There are many people who loved Hoffman's acting. But if you don't, you're not wrong. At worst, you're eccentric.
(An interesting question—and one you didn't ask so I won't answer it, here—is why are there trends? Even if Hoffman isn't ...(more)