The beat the song is built on is a 2-bar phrase, played through bars 3-5, 37-39 and 41-43, and 4 more places -- 16.8% of every bar the kit plays. This one moves around more than most: the beat is where to start, not the whole job.
It is played on crash, hi-hat, snare and kick, counted in thirty-second notes. On its own it scores 69 out of 100 -- demanding -- and the thing that decides that is how much of it falls off the beat.
The whole song is 90 out of 100, so the beat is not the hard part: what costs you is everything around it, the joins and the fills.
A part this hard is not learned by playing it slowly and hoping. The room opens it on its simplest reduction -- the timekeeper alone, at 55 BPM -- and adds the notes back over 4 rungs, each with a tempo to reach and a gate to pass before the next.
Tempo goes 55, 65, 75 and 85 BPM, and the gate at each one is 8 loops in a row with no wrong note and no wobble in the time.
PRACTISE THIS BEAT →A 2-bar phrase on crash, hi-hat, snare and kick, in 4/4 at 85 BPM, counted in thirty-second notes. It is written out above, and it covers 16.8% of the bars the kit plays.
Bars 3-5, 37-39, 41-43 and 62-64, and 3 more places. The time is kept on the snare to start with, and it changes 14 times over the song.
69 out of 100 on its own -- demanding. The song as a whole is 90 out of 100. Hard, and what makes it hard is how much of it falls off the beat.