It would be incredibly difficult to implement an objective, studious method for determining strength of board position. As well, most games do use such a method when determining board positions. Most games use a secondary numeric value when determining strength of schedule and tie breakers. An interesting method Mage Wars could use is recording who won (represented by 2n, where n is the number of rounds won), and then recording the differential damage between the winning and losing mage (represented by L-W, where L is losing players damage total, and W is the winning players damage total). These would be recorded each round as follows:
G1, I won, and the opponent took 38 damage, and I took 17. 38-17=21, so I would record 2 (27) on my score sheet.
g2, I lost, and the opponent took 19 damage, and I took 32. 32-19= 13, so I would record 2 (40) on my score sheet.
IF the game came down to a tie due to time, players would split the points, so each player would receive 1 point apiece. You would still record damage differential as normal. Note that you may have a negative total in this column, but that is okay.
If, in cutting to the top eight, two players have the same match point number (in my example two), then we would go by the higher damage differential recorded.
This is just a rough idea, but I think it most effectively implements what you folks are tackling. Cheers!
Padawan