Because it was the draft best (highest grade) player available philosophy. I think Saints had a high grade on Ruiz but due to him being a center he wasnt drafted high by other teams. I remember there was a group of people who believed best player available was best because you never reached and when its time for a contract you would have a good player ready to go. I agree Center position was baffling, I still think Ruiz should be playing center BUT We took the same approach with Alvin Kamara, we had Mark Ingram and signed Adrian (AD) Peterson. Also I think it has to with the Parcells influence on Sean Payton. I dont remember exactly where I saw it but Something like Parcells Told Payton if someone has like freakish size and athleticism draft those players because they are rare. I definitely messing up the quote but If you notice we always Draft Big Athletic guys, Davenport, Peat, Ruiz, Turner, Rankins, Ellis best happen to Be Cam Jordan by far.