Some days, it looks like it!
No, actually I do have a system I use, a power rating and current form basis that derives a "line" on each game... when my line is .20 cents or more difference, I mark it a play. The power ratings reflect the overall performance of a team, and doesn't factor in individual starting pitchers as much, but more so the overall power of the staff, including the BP.
I'm planning on charting it the rest of the year, then crunching the numbers to see if I can reduce the number of plays in a day, and increase the win %. But, so far, it's been doing fine on it's own, so I'm not messing with it. Maybe after the season, I'll plug the numbers and see if I can increase the win % by moving my line difference to say, .30 or .40, but for now, it's staying put.
The one day I "tried" to cut down on the plays, reducing them from 12 to 8, the games I scratched went 3-1 for +3.65 Units!
As the old saying goes... "if it ain't broke,..... "