I'm pretty sure that Patrick has played a lot of Center in his career and while Ruiz played Center in college, I don't think he's taken many snaps, if any at Center in practices with the Saints. I don't recall hearing him playing Center at any point in camp this year which would make it hard to move him to Center in a week.
Patrick is the backup Center so I wouldn't be surprised to see them stick with the same guys this week or just put Landon Young or Saldiveri at LG. Someone mentioned that Hergel took some snaps at Center during camp so maybe they could put Hergel at Center while keeping Patrick at LG and Ruiz at RG to reduce the number of moving parts.