My book lists McCutchen as starter but MLB network says its Zack Duke... if this is the case then the line should come way down. Duke has a much better chance to win this and if you play "action" you will get the +230 range for this game....
No you won't.
If you play "Action", and McCutchen pitches, you will get +230.
If you play "Action", and Duke (presumably the superior pitcher) pitches for Pittsburgh, you will get the "Adjusted" Line.
In other words, whatever the line is when the book puts up their "new" line on Pittsburgh to reflect the pitching change, that's the line you will get. If the book puts up +160 on Pittsburgh (with Zack Duke as the Listed Pitcher), +160 is the line that you will get.