Very hard to take a roller-dyno of an electric car at face value. Rollers have a problem with cars that produce lots of torque right at the get-go... and with no gears and an electric motor, the Tesla produces a crapload of torque at the get-go... which is why we typically dyno newer cars in fourth or fifth gear (helps give you a longer pull to get the turbo spooled up, too).
Also have no clear read-out of torque versus rpm and/or road speed... which is much more important. Also no word of SAE corrections, which would have been silly to apply, since it's not a gasoline motor...
...but some machines do this automatically, anyway.
Granted, the performance of the Model S in terms of 0-60 does suggest it really makes that much power at the wheels. That is one hot momma.