If I understand your question correctly: YES the Pro service allows you to choose the alternate lines.

E.g. the current line is let's say New England +3, at 55%

You want to know what the % is for +2.5, there's a point spread analysis that will display the new percentage.

Same goes with the over/under line.

The system itself cannot compensate for variables such as atmosphere or weather or rivalry's. Those things you cap in on your own. Keep up the good work over here and if you didn't have any negative's then you can never get a positive.