I out right blow when it comes to Over/Unders...is there any better way of running numbers other than....

taking past 5 games Offense, dropping high and low, averaging with other teams Defense from same 5 games minus high and low? and same goes the other way, defense of "team a" to offense of "team b".

This is the only way I know of doing it...and it doesnt work very often.

Any advice?