Why is Texas on the North. USC on the North. It seems Marshall is on the north then the next year it's the south???

The Senior Bowl switches some teams around depending on the number and quality of the players. Generally, the SEC gets overrepresented so usually there are some strange "North" teams from the Big XII.

They've always done it that way. But also remember, the point of the game isn't to have a true matchup between regions, but to provide NFL scouts an opportunity to evaluate college talent. And the game itself isn't nearly as important as the practices

Obviously, there's the home crowd in Mobile to make happy so the SEC always plays as the South.

I've also in the past seen injury replacements from northern states get put on the South and vice versa.