I do not think the number of regiments from East Tenn. is any indication of how the peopl;e of that area divided.
Especially early in the war when the Confederate government was in control, many pro-unionists fled to Kemtucky and joined Ky. regiments there.
When the federals entered the area and were often in control, others joined existing Union regiments regardless of the state of origin of that regiment.
Until quite recently, the Republican tilt of East Tenn. could be accounted for, at least in part, by lingering Civil War loyalities.
Over 100,000 Tennesseeans joined the Confederate army but 40,000 joined the Union army. Such statistics were suppressed by post-war die-hard rebels as they sought to portray the South as solidly behind the Confederacy.
I know of families in Middle Tenn. that were divided in their loyalties with menbers in both armies and a few individuals in BOTH.