Note that the Black Caps is the nickname for only the national cricket team of New Zealand and not for their other national teams. Accordingly, the title and text have been corrected. For example, their national hockey team is referred to as the Black Sticks. You can look up the interesting information given in Wikipedia of the origin of the nickname Black Caps (https://en.wikipedia.org/wiki/New_Zealand_national_cricket_team).
Also, note that the Australian national cricket team is referred to as 'Baggy Greens' with reference to their green caps which, well, look baggy. The English national cricket team as such has no nickname, though I recall reading somewhere or from some movie that they are sometimes called "Poms" (why I don't know). The Barmy Army is not their nickname at all, but refers to the group of fans which go to cheer their team in the stadium with various musical instruments.
When you make a commitment, you create hope. When you keep a commitment you create trust! ~ John C. Maxwell