An interisting use of a collective noun.
Nouns which stand for a group of people/ things are a special case.
Examples are, Team, Band, Herd. If I consider a football team to be one unit, I refer to the team in the singular; but if I think of the team as being made up of individual players, I refer to the team in the plural.
Therefore: "Shamrock Rovers is an excellent team" is grammatically correct, but so is "Shamrock Rovers are an excellent team".
GRAMMATICALLY correct , I said. :o)