while some may disagree with this - ive never put much stock in a "-1 to +1" line flip. what im saying is that if texas tech went from -1 to -3, then yeah- a red flag might go up. but i dont value a "-1 to +1" line flip very much. since "zero" is essentially a dead number, sometimes the line will just flip flop between who is laying the point (instead of settling on pick for a little bit)
hopefully that makes sense.
in a nutshell- i just feel like a "-1 to +1" line flip is really a one point move, even though a number line would tell you its a two point move.