I'm most concerned about the Joe Thomas loss. That guy was a generational talent at the OL.
I find it hard to believe that a 27 year old is considered "up and coming," but it's widely accepted that a OL at the age of 29 or 30 is "too old." ProFootballFocus graded him
below average as the #40 T in the league. Perhaps he takes the next step this season and has 2-3 very productive years, but "one of the best up and coming offensive linemen in the league" is likely a gross over-statement
Shon Coleman was rated as the 51st best T in the league and was graded
"poor" by PFF. But I will give you that he could be an eventual competent starter given I don't know much about him and it's not uncommon for mid round OL to sit for a year or two.
Regardless, it sounds more like wishful thinking that a 27 year old that has yet to "make it," a 3rd year 3rd round Tackle switching positions, and 2.01 rookie are going to over-come losing one of the best Tackles we've seen in over the last decade or two and be an upgrade in general from last season's line. But, your guess is as good as mine, so I guess we will see in a few short months.