Now that you mention region strength, the following is the average of the eight teams SOS in each region and the teams that made it out and their SOS:
Region 1 - 45 (Tennessee SOS 94)
Region 2 - 61 (Powell SOS 55)
Region 3 - 70
Region 4 - 38 (Blackman SOS 13, Cookeville SOS 11)
Region 5 - 41
Region 6 - 81 (Hillsboro SOS 91, McGavock SOS 66)
Region 7 - 76
Region 8 - 38 (Memphis Central SOS 10, Memphis Overton SOS 12)
That puts Hillsboro and McGavock in the weakest region just behind Region 7(Millington), but both Hillsboro and McGavock and been ranked the top ten in middle tennessee for most of the year and they beat two teams(Wilson Central and LaVergne) from a region with a much stronger SOS of 41.
One of the strongest regions, #4 has Blackman and Cookeville, both of which consistantly ranked out of the top ten behind Shelbyville and Riverdale.
Playing a tougher schedule can certainly help prepare a team even in a loss, but if they peak to soon or have bad matchups, the numbers don't mean much.