The author of this piece actually did some research.
Selection committee chair Bernard Muir told ESPN that a team's specific NET ranking was not intended to be the determining factor in the committee's choices.
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However, speaking after the selection show on CBS, Muir said the committee examined how well teams did against opponents in the NET rankings' top quadrant. He noted that a team like Belmont, which went 2-2 against Quadrant 1 teams, was looked upon more favorably than a team like NC State, which went 3-9 against Quadrant 1 opponents, and therefore did not make the most of having more opportunities for Quadrant 1 wins.
Clemson was just 1-10 against Quadrant 1 teams, while Texas, with a NET ranking of 38, went 5-10 and also settled for the NIT. St. John's, despite its much lower NET ranking of 73, went 5-7 against Quadrant 1 teams, the most wins of all the Last Four In and First Four Out teams other than Indiana, who went 6-9 against Quadrant 1. But St. John's also went 5-3 against Quadrant 2, whereas Indiana was just 2-6.