I doubt it was the final straw. That was just one game, and we were highly competitive with the best team and best coach in the country. I hope that White doesn't make a one game "shouldawonit" a significant part of his decision. Kellie was fired for poor high school recruiting and a history of failing to finish higher than third in the SEC and finish beyond the Sweet Sixteen. If any one game was the final straw, I'd guess this season's round of 32 game was it.
Seems like maybe you don't understand the phrase "the final straw," 'cause the final straw means that there were many, many other straws (reasons to fire her) that had come before, but then that last reason -- straw -- was juuuust enough more to make the weight of her problems too heavy to hold.
So, no, of course it wasn't that one game. But the public humilation caused by that one game may have sent DW past his point of tolerance.