The Saints were terrible last year in short yardage. So, what do they do to fix that? They bring in one of the better short yardage RBs in the league last year. Williams is exactly what the Saints needed. He was never expected to be more than that. I don't know why that's hard to understand.
This is just my personal opinion, but I wouldn't have paid $12 million for a short yardage back. Now if he was running like Jamal Anderson, I would be totally fine with that.