That's the point though. There's not one answer. Depends on the situation and how it's being used.I think you are mixing examples. This year's Crimson Tide is one team, a singular unit, a collective. It's an "it", not a "they" in pronoun terms.
I believe that when referring to a team by its nickname, collective nouns take the plural form. Thus, the Crimson Tide and the Tigers both are plural. This is why when someone asks how your team fared, one normally replies that WE or THEY won/lost, not IT won/lost. If someone asks how many first downs the Bears have, the normal reply is "They have 13 first downs." Not, "It has 13 first downs."
It's fourth and one, what will the Crimson Tide do? They're going for it! Would be pretty rare to hear anyone say IT'S going for it.
It's tough when team nicknames are singular (Crimson Tide) versus plural (Tigers); but in context you should treat them the same. And you would never say the Tigers IS playing well.