cc @ColinTheMathmo
Note: the 5 is always trown with the blue ball, and
the 2 is not actually thrown: the ball remains in the hand for 2 beats.
Just two balls, but not so easy!
The average of the numbers in a siteswap is the number of balls you need to juggle that trick.
e.g. 53 needs 4 balls
eg 523 can't be valid because (5+2+3)/3=10/3
You can juggle 123 with (1+2+3)/3=2 balls, but not 321 as shown here