It sure is strange that Tennessee provided so many regiments to the Confederacy, if they were as "loyal" as you say. I disagree, I think the state was divided a lot more evenly than you think.
The western two thirds of the state was much more traditionally southern and I think that most of Tennessee Confederate soldiers came from Middle and West Tennessee. But the mountain East Tennessee was really a state unto itself. To be sure there was a number of East Tennesseans who fought for the confederacy out of true conviction. But a lot of those who appeared on the rolls were like my ancestor's regiment and were pressed into service. A number of people in my family were in that situation and escaped to the Union army at first opportunity.
There still is a residue of that regional differentiation today. It wasn't long ago when highway signs at the border welcomed visitors to "The Three States of Tennessee".