From what I understand on Franz, he is being brought in as a backup safety and a special teams player. I highly doubt he will be starting. I think he is similar to a Scott McGarrahan or Antuan Edwareds.
I also think that the Rugamer signing was a good move. He is a reliable backup, but not so sure about a full time starter. At the end of the year, Bechtol said he liked Wells at center better than Ruge. The only reason he started in the playoffs is because of experience, not tallent. I think they might sign or draft someone else to challenge Brad Bedell, Atlas Herrington, Wells, Rugemer, and Kevin Barry and then take the top 2 performers and plug them in. There's also a Joe Quinn and Joseph Hayes on the roster at the Guard position who I haven't heard of before.
One thing I think would be cool is if you could get your guards to know both the left and right sides and have them switch during the games. You have one who is a bulldozer a la Larry Allen of the Cowboys, and one who pulls like Wahle. Then if you flip flop them and run both plays to both sides, the Defense wouldn't be able to plan for running tendencies at all. Grant it, that would take a lot of time to learn, but I think that some of the guys could be up for it.