[smcl]

This is in danger of running into the back/forth that we saw in the Angels and Airwaves Wikipedia page :-)

Joking aside, it might sound odd to an American (or Canadian?) but British English would not distinguish between whether or not the name or “nickname” are singular or plural. So we would say:

The Seahawks are winning

Seattle are winning

Arsenal are winning

Rangers were relegated

I think this is the kind of thing where you can learn to tolerate the “wrong” one but it’ll always sound weird to you, whether “wrong” for you is British or US English :-)

Edit: I did think of a situation where we’d use “is” - when you’re referring to the legal entity or FULL name of the club. “Aberdeen Football Club is a Scottish professional football club based in Aberdeen”. This is pretty rare to see, and you’ll likely just see it in, ironically enough, the first line of a Wikipedia page.

[nwallin]

"The" and the postscripted "s" imply plurality, and therefore the use of "are". Nearly all sports teams in the US are pluralized, so it would be "the Seahawks", "the Bears" etc. There are a small handful of counter exactly examples, such as the Utah Jazz and the Miami Heat. But I think most sports fans use their standard sports lexicon that they use for every other team and treat team names as plurals.

Band names tend to be mixed. It's clearly "the Red Hot Chili Peppers are playing at..." but also "Primus is playing at...". (See also the edit war between "The Eagles" and just "Eagles")

[SAI_Peregrinus]

I think the use of "The" as part of the name also matters.

"The Patriots are winning" sounds OK to me as an American. "The Patriots is winning" sounds totally wrong. "Arsenal are winning" sounds fine, "Arsenal is winning" also sounds fine.

[ghaff]

When I think of American sports teams there's usually an understood "The" in front. "Patriots are winning" works fine conversationally but, if you were being a bit more formal or writing it down, you'd say "The Patriots are winning." On the other hand, the city name is singular. "Boston is winning."