Seven years in California taught me (eventually – the hard way) to not correct people's pronunciation of their home towns; I learned to just quietly grit my teeth, and let it go.
And I have the good sense to not mess with Texans about what happens to the last syllable of that Big River that separates their state from Mexico, when Anglo-Texans pronounce it. I just don't reckon they'd take all that kindly to it.
But I've got to draw the line with the NFL. Whether Jacksonville's team is meant as a tribute to a South American wildcat (JAG-wahr), or a British automobile (JAG-you-AHR), their is no precedent, and no reason for why they would call the team the 'JAG-wires'.
That is all ... You're Welcome!