I actually don't think that it's too crazy. Willis actually has looked good when he's had his opportunities in Green Bay. He came out of a broken Tennessee team that has drafted him, then Levis, then Ward, all without much success.
The issue I see is that unless Stafford decides to retire, I don't see us spending high on a quarterback this year. We're not the only team Willis could go to, and with the now complete dearth of actual good quarterbacks in this class (aside from Mendoza and Simpson with Moore, Sellers, Sorsby, and Mensah either very likely returning or confirmed to return to college - and even Simpson could end up returning - it's very bare.), I could see some teams paying through the nose to get a potential starter in free agency, and Willis might be the best young guy with potential on that list.