The vents on the baffle only seem to equalize the balance of low to high frequencies, I wouldn't call them absorbers.
In their marketing Sennheiser claims the following:
"The patent-pending curved Gorilla glass serves to reflect the sound waves from the rear of the transducer to two absorber chambers, which results in minimal resonance."
I suppose by "absorber chambers" they mean the two cylindrical extrusions that can be seen in this picture: https://www.superbestaudiofriends.org/index.php?attachments/img_1103-jpg... (right above the Sennheiser logo)
They are probably two Helmholtz resonators that get rid of two peaks.
I think that's pretty good. Instead of stuffing the thing with foam and hoping for the best they are creating an environment with predictable peaks that are then tuned out with anti resonant resonators. That seems like an elegant soloution and also enables them to put the nice looking window on the cup.
And now we wait six months.
Also I think Axel doesn't like you anymore after you knocked his headphone of the WoF right after calling it the World's best headphone :^)