[mesmark]

Most team names are plural in form and always expressed with a plural pronoun.

The Yankees are doing worse this year.
They have lost three straight at home.

I tend to use other group words as singular if they are singular in structure, but still use plural pronouns.

The Back Street Boys have yet another album coming out.
Aerosmith is currently on tour.

I think it depends on whether you refer in your sentence to the group as a whole or as made up of individuals.

New Kids on the Block is reuniting after X years.
The New Kids on the Block are much older than I'd have guessed. A few are in their 40s.

The couple next door is coming by for tea later. (single entity)
The couple next door are two of the best singers I've ever met. (made up of individuals)