He would be the best pass blocker of the 3 from last year's play, but the worst run blocker of the 3. Eli is better overall and needs to step up in the pass game from his guard play to take the job. He should easily be able to do that. Id say Ciraco in pass pro is the bare minimum for what we need at C, and Eli run blocking is the minimum on that side.
We haven't seen significant snaps from Eli at C in ages. It looked to me that he struggled out of position at Guard, which is not common but does happen (Yoshi is the biggest example). And that he, like everyone else, struggled with kola at C. I expect to see a significant improvement from him going back to his natural position full-time. If not, I'd cut him. I would expect to see that increase in the level of play before the first preseason game.
Ciraco would be the backup plan imo. If we missed out on Woodmansey, I'd take flyers on guys like McEwen. Failing that, I'd try to target a C in the draft if possible.
Ciraco would be the guy I would look to bring in during camp, if Eli fails, we don't get another FA, and Vibert doesn't step up. Basically, the contingency plan is the backup plan.
He's a good pass blocker, but he fits our system really poorly. We'd have to give up on our zone run scheme, and even then, he isn't a guy who is going to feast in any run scheme.
I believe in Eli, and I also really like Vibert. But I would bring in a plan A, and look long and hard at Cs in the draft.