I would say Trever Penning and Nick Salvideri are the very definition of "uncertainty." Penning was benched and not trusted in even jumbo packages last season and Salvideri has 18 career snaps.
Do I hope both turn into all pros? Absolutely, but you can't say we know anything about how either of these guys will play. I mean, McCoy and Ruiz may be the only veteran starters next year. This might be the most uncertain/inexperienced Oline we have had in years.
But I only mentioned Penning/Salvideri going off of Triplett's article. We have NO IDEA who will start on the left side this season. Again, more uncertainty.