"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")