I hate to tell people this, but... the only thing the Bears did with the Oline is replace Charles Leno with a rookie. Nothing else has been upgraded. If anything, while he may not been worth the money he would have made, Leno was the most durable Oline men the Bears had. All the other projected starters missed time last year, and it seems the team Mustipher at Center, if they seem to be running Bars on the first unit and Whitehair at Center.
For all we know, Jenkins could be an upgrade over Leno and an All pro Lt waiting to burst out, but at the end of the day you are an injury or two away from having another rookie or worse scraps and 2nd 3rd string level Oline men starting again.
So unproven rookie LT
A guard playing Tackle,
A guard playing Center.
A guard coming off an ACL injury.
And last, a guard who has been mostly considered a practice squad player until this year.
This line is unproven and 3 players are considered out of position, considering Jenkins historically plays more like a right tackle then left.
That said I hope the Bears can be a top 15, or top 10 Oline this year, but I think think is still a work in progress, and we as a team still lack pieces there. Getting a guy like Jenkins is a step in the right direction, but I feel more steps maybe needed.