IMO, it's a ridiculous name for the field anyway. In addition to the "singular, plural, possessive" oddness of the name, the field is named for someone who never set foot in the Dome. He is honored in enough other ways - the field thing is overkill.
What is the intention? Is it Ernie Davis' Legend's field? Is it his legend? That would be possessive and if it's Legend's field, it belongs to the legends. I guess it just depends what SU means, or I am an idiot that isn't good at English.
I have no idea how something like this happens. And it has gone viral on the web a bit so its a minor black eye for the school. It should be a quick and easy fix and there is no excuse if it isn't corrected by Saturday's game vs Wake