No one knows this. Flemming right now is a talented unknown.
I think you guys have repeated the word "swing tackle" so much that you've convinced yourself w/o even really knowing what the term means.
A swing tackle is a backup. After 4 years or so at NE filling the extra OLineman role, it's highly unlikely that Flemming is coming here just to be a backup, and it's also highly unlikely that we signed him strictly to be a backup.
At NE, Flemming filled the role of extra blocker. So, can he start? Odd are that he is not a bad starter. And w/ our big 3, we just need solid at the other two positions. I don't know how this will play out, but it could easily be that Fleming and Lael are both starters wherever they are needed. At present, I doubt if we have a better player than Fleming as the 5th OL.