1. MTSU had a better year.
2. MTSU won their last seven, including their Bowl Game.
3. Minnesota lost their Bowl Game and five out of their last seven, scoring 16 or less in their last three games.
4. Minnesota's Offense was awful, Weber's still the QB and the Defense lost nine starters.
The line reflects what they guess the public's thinking to balance the betting. The general public and even some people on this board focus on the above for things.
That makes MTSU the favorite it's logical and yeah, it sucks.