A football sock has one job before it has any other, and four specifications decide whether it does it.
Ask for elastane content
It is the number that sets how much the tube grips the leg.
Nobody volunteers it, and every serious knitter can tell you.
Ask for recovery, not stretch
Stretch on day one is easy. Returning it after fifty hot washes is the product.
A sock that sags in November did not shrink; it stopped recovering.
Check the band
Depth and tension decide whether the top rolls or the leg gets marked.
Youth sizes need a shallower band, not a smaller version of the adult one.
Foot and leg are different garments
Cushion the forefoot and heel. Leave the leg an even tube.
Terry under a shin guard is bulk that lifts the guard off the leg.
And skip cotton
It holds sweat against the foot inside a boot for the whole match.