A tweak was made to the design in 1911 when the club were promoted to the top division (the Eerste Klasse). Away kits didn't exist, so to prevent a clash with Sparta Rotterdam, Ajax changed to their now legendary thick red vertical stripe. The player in the crest was changed to reflect the new kit design.
This era saw Ajax become Dutch Football League Winners for the first time, in the 1917-18 season.
The crest stayed the same until 1928, and a radical change to reflect the club's name. Named after the mythological Greek hero "Ajax", his head was used in the design along with the name. It was quite arty, and quite elaborate, but instantly recognisable. This Ajax crest was used for more than 60 years, through the glory years of the 1970s when they ruled Europe (they were European Cup winners three seasons in a row at the start of the decade), often appearing as a huge badge on their training gear.
In 1990 Ajax decided that the "Ajax head" needed a more modern look, mainly for commercial reasons.
So a more abstract design was done, the head made up of eleven lines, each representing the eleven players in the Ajax team.