: The Covenant did screw up on a potential galactic level of extermination.
: Chief and Cortana released someone so powerful that he could pick Chief up
: with his mind, throw him around, and really do whatever he wanted, but
: instead mostly floated about in a giant ball before getting defeated by
: (Cortana) light and a grenade. Oh man, what a bad guy there. Watch out
: galaxy. Chief, you stupid fool, you released a nobody who really only sort
: of threatens humanity and is nothing compared to the Flood and was
: actually pretty much destroyed by the Flood in a previous lifetime along
: with the rest of the Forerunner. Way to go Chief.

Don't forget, though, the Flood isn't all that dangerous. I mean, the Librarian called us "The Forerunner's most tenacious foe" or something like that, and our fight with the Forerunner only ever amounted to a border conflict. That means that the Flood couldn't have been worse than, say, a really bad flu season.