What constitutes craftmanship?

I wonder if anyone noticed that Gustafsson's 'Sestina' operated within strict formal constraints? That there are only six rhymes throughout, which vary during the sestets and are compressed into internal and end rhymes in the final tercet?

Here is another scheme:

xXxxX, xXxxX
xXxXxxXx
xXxxX, xXxxX
xXxXxxXx
xXx, xXx
xXxX
xXxXxxXx

the capitals indicate stress, the different colours different rhymes.

Who is capable of writing a wonderful poem of 22 stanzas within these constraints? The next blog will tell you. The poem is from 1642.