He picked Lucey because he couldn't get a prominent Democrat on the ticket. Lucey was the only one willing to do it. In retrospect, he could've chose John Lindsay, Edward Brooke, or someone like that.
He picked Lucey because he wanted someone that loathed Carter. I read in a book (and I have a source) that says on election night, Lucey's wife was fixing his tie and telling him "smile Carter is not elected."
Source: Rendezvous with Destiny by Craig Shirley
It'd be interesting to see a timelien with an Anderson victory, and have that part happen right before Anderson's inauguration.